M-coated Ru / gamma-Al2O3 core-shell catalyst and preparation method thereof, and method for preparing MACM through MDT continuous hydrogenation

Abstract

The invention belongs to the field of material intermediates, and relates to an M-coated Ru / gamma-Al2O3 core-shell catalyst, a preparation method thereof and a method for preparing MACM through MDT continuous hydrogenation. The core-shell catalyst comprises a carrier and a loading component; the carrier is gamma-Al2O3 loaded with an alkaline metal oxide; the alkaline metal oxide is one of CaO, MgO, BaO, La2O3 and SrO; the load component takes metal M as an inner core and takes metal Ru as a shell; the metal M is selected from any one of Mo, Mn, Co, Zn, Cr and Re. The conversion rate of MDT reaches 99.9% or above, the selectivity of MACM reaches 98.3% or above, the content of the first isomer in the MACM product is 26.7 wt%, in addition, the service life of the catalyst is long, the one-way operation life of the catalyst is 2000 h or above, and the catalyst has good industrial application prospects.

Description

Technical Field

[0001] The invention belongs to the field of material intermediates and relates to a M@Ru / γ-Al2O3 core-shell catalyst and a preparation method thereof, and a method for preparing MACM by continuous hydrogenation of MDT. Background Art

[0002] MACM (3,3'-dimethyl-4,4-diaminodicyclohexylmethane) is widely used as a chain extender and auxiliary agent in epoxy resin curing agents, epoxy coating curing agents (such as ship paints, heavy anti-corrosion paints, etc.), epoxy composite material curing agents (such as wind blade curing agents, wind mold material curing agents, etc.), and for the preparation of synthetic polyurethane (PU), polyurea spray elastomer (SPUA), etc.; MACM can also be used in the synthesis of polyaspartic acid esters, polyamides (PA), etc.

[0003] The polyurethane synthesized by MACM has both the elasticity of rubber and the strength and excellent processing performance of plastic, especially in terms of sound insulation, heat resistance, wear resistance, oil resistance, elasticity, etc., which are unmatched by other materials. The synthesized polyamide is non-toxic and light, and has excellent mechanical strength, good wear resistance and corrosion resistance. In recent years, the application of MACM has expanded rapidly at home and abroad, and MACM with excellent production performance has great industrial and commercial value.

[0004] Patent US2010 / 292510A1 discloses the use of a high pressure reactor, at a temperature of 230 ° C, a pressure of 27 MPa, MDT is catalytically hydrogenated by Ru / SiO2 to obtain MACM, and the product yield is 75%. Patent WO2009090179 discloses a method for obtaining MACM by liquid phase catalytic hydrogenation of a liquid melt of MDT under the action of a Ru catalyst at 200 atmospheres and a temperature of 230-240 ° C; Patent WO2009153123 discloses the use of a RuO catalyst at 200 atmospheres, a temperature of 180-240 ° C, and MDT liquid phase catalytic hydrogenation to obtain MACM. In addition, Albemarle Corporation's patent WO2010005859 discloses the use of 2-methyltetrahydrofuran as a solvent at 70 atmospheres and a temperature of 30-185 ° C to obtain MACM by hydrogenation of MDT in the presence of a Ru catalyst. Chinese patent CN201010558412.9 improves the production process of MACM, and the product MACM and the raw material MDT are put into the reactor at a ratio of 1:1-4, and Ru catalyst is added, and a trace amount of alkaline earth metal additive is added, and catalytic hydrogenation is carried out at a temperature of 120-190°C and a pressure of 20-100 atmospheres to prepare MACM. The MACM synthesis methods reported in the existing literature are mainly concentrated in batch production, with relatively low catalyst activity, high reaction temperature, and low selectivity of the target product MACM.

[0005] The reaction equation for preparing MACM by hydrogenation of MDT (3,3'-dimethyl-4,4'-diaminophenylmethane):

[0006]

[0007]

[0008] The first isomer of MACM

[0009] The existing processes all use intermittent kettle hydrogenation process to obtain MACM, which has low production efficiency and high labor intensity. With the continuous expansion of MACM usage, it is urgent to develop a continuous production process for MACM. The development of high-performance catalysts is crucial. On the one hand, the catalysts must be highly active, able to significantly reduce the reaction temperature and reduce the generation of impurities. On the other hand, the catalysts must be resistant to sintering and have good stability. Summary of the invention

[0010] In order to solve the problems in the prior art, the present invention provides a preparation method of a M@Ru / γ-Al2O3 core-shell catalyst and its application in the reaction of continuously hydrogenating 3,3'-dimethyl-4,4'-diaminophenylmethane (MDT) to prepare 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane (MACM). The M@Ru / γ-Al2O3 core-shell catalyst has high catalytic activity for hydrogenating MDT to prepare MACM due to the electronic effect of the metal promoter, greatly reducing the reaction temperature. At the same time, due to the core-shell structure of the catalyst, the catalyst has good stability.

[0011] In order to achieve the above-mentioned purpose, on the one hand, the present invention provides a core-shell catalyst, comprising a carrier and a loading component; the carrier is γ-Al2O3 loaded with an alkaline metal oxide; the alkaline metal oxide is one of CaO, MgO, BaO, La2O3, and SrO; the loading component has a metal M as a core and a metal Ru as an outer shell; the metal M is selected from any one of Mo, Mn, Co, Zn, Cr, and Re.

[0012] In order to further reduce the formation of polymers, the γ-Al2O3 carrier needs to be modified with alkaline oxides such as CaO, MgO, BaO, La2O3, SrO, etc., that is, the core-shell catalyst uses γ-Al2O3 modified with alkaline metal oxides as the carrier, the metal additive M as the core, and the active metal Ru as the shell.

[0013] As a preferred technical solution, the metal M is an auxiliary agent and the metal Ru is an active component.

[0014] As a preferred technical solution, the mass of the metal additive M is 0.5% to 10.0% of the total mass of the catalyst;

[0015] As a preferred technical solution, the mass of the Ru is 0.1 to 10.0% of the total mass of the catalyst.

[0016] As a preferred technical solution, the mass ratio of the alkaline metal oxide to γ-Al2O3 is 1 / 30 to 1 / 3.

[0017] On the other hand, the present invention provides a method for preparing a core-shell catalyst, comprising the steps of: in an inert atmosphere, a mixed system containing γ-Al2O3, a solvent, NaBH4 and an M precursor is subjected to a reduction reaction I to obtain M / γ-Al2O3; a dispersed system containing M / γ-Al2O3, water, a Ru precursor and hydrazine hydrate is subjected to a reduction reaction II to obtain the core-shell catalyst.

[0018] As a preferred technical solution, the solvent is a mixture of ethanol and water, and the volume ratio of ethanol to water is 1:1 to 1:10.

[0019] As a preferred technical solution, the inert atmosphere is selected from at least one of nitrogen, argon or helium.

[0020] As a preferred technical solution, the precursor of the metal Ru is selected from at least one of ruthenium trichloride, ruthenium acetate, and ruthenium acetylacetonate.

[0021] As a preferred technical solution, the M precursor is at least one of nitrate or acetate.

[0022] As a preferred technical solution, the conditions of the reduction reaction I include: temperature of 10 to 60° C., normal pressure, and reduction time of 1 to 6 hours.

[0023] As a preferred technical solution, in terms of mass ratio, γ-Al2O3: solvent: M precursor: NaBH4 = 1: (2~8): (0.2~1.0): (0.05~0.5).

[0024] As a preferred technical solution, the conditions of the reduction reaction II include: reduction temperature of 50-90°C, normal pressure, reduction time of 3-9h; in terms of mass ratio, M / γ-Al2O3: water: Ru precursor: hydrazine hydrate = 1: (1-10): (0.5-3.0): (0.1-1.0).

[0025] As a preferred technical solution, the method further comprises the step of drying the core-shell catalyst, and the drying conditions include: drying temperature of 110 to 150° C. and drying time of 6 to 12 hours.

[0026] Preferably, the γ-Al2O3 carrier is modified with an alkaline metal oxide, and the precursors of CaO, MgO, BaO, La2O3, SrO, etc. are prepared into a salt solution, which is impregnated on the carrier γ-Al2O3 by an equal volume impregnation method, dried at 120°C for 4 to 12 hours, and calcined at 400 to 900°C for 2 to 9 hours.

[0027] As a preferred technical solution, the method also includes a step of reducing the core-shell catalyst, and the reduction conditions include: a reduction temperature of 200 to 500°C; a reduction time of 3 to 12 hours; a reducing atmosphere of hydrogen, and a volume space velocity of 50 to 500 h -1 .

[0028] On the other hand, the present invention provides a method for preparing MACM by continuous hydrogenation of 3,3'-dimethyl-4,4'-diaminophenylmethane (MDT), wherein 3,3'-dimethyl-4,4'-diaminophenylmethane (MDT) is contacted with a catalyst, and a continuous hydrogenation reaction occurs to prepare 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane (MACM), and the catalyst is any one of the above-mentioned core-shell catalysts, or a core-shell catalyst prepared by any of the above-mentioned methods.

[0029] As a preferred technical solution, the conditions of the hydrogenation reaction include: reaction pressure of 2 to 10 MPa; reaction temperature of 90 to 220°C; feed mass space velocity of 3,3'-dimethyl-4,4'-diaminophenylmethane (MDT) of 0.1 to 1.0 h -1 ; The molar ratio of hydrogen to 3,3'-dimethyl-4,4'-diaminophenylmethane (MDT) is 10 to 80.

[0030] As a preferred technical solution, the conversion rate of 3,3'-dimethyl-4,4'-diaminophenylmethane (MDT) is ≥94.6%, preferably ≥97.6%, preferably ≥97.8%, and more preferably ≥99.9%; the conversion rate of MDT is selected from any value among 94.6%, 96%, 96.3%, 97.6%, >97.9%, 97.8%, 98.4%, 98.9%, 99.5%, 99.7%, 99.8%, 99.9%, or any range value between two of them.

[0031] As a preferred technical solution, the selectivity of 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane (MACM) is 95.4% to 98.7%, and the selectivity of the MACM is selected from any value among 95.4%, 96.4%, 97.6%, 97.8%, 98.0%, 98.1%, 98.3%, 98.4%, 98.5%, 98.6%, 98.7% or any range value between two of them.

[0032] As a preferred technical solution, the content of the first isomer in the 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane (MACM) product is 21% to 30%, preferably 21.6% to 29.8%. The content of the first isomer in the MACM product is selected from any value or any range between two of 21.6%, 22.9%, 24.3%, 24.7%, 24.9%, 25.9%, 26.0%, 26.1%, 26.3%, 26.4%, 26.5%, 26.6%, 26.7%, 26.8%, 28.4%, 28.9%, 29.6%, 29.7%, 29.8%.

[0033] The first isomer of 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane has a structure shown in Formula I,

[0034]

[0035] As a preferred technical solution, the yield of 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane (MACM) is 92.0% to 98.5%.

[0036] Compared with the prior art, the technical advantages of the present invention are as follows:

[0037] (1) Due to the electronic effect of the metal promoter, the catalyst has a high catalytic activity for the hydrogenation of MDT to prepare MACM, which greatly reduces the reaction temperature and reduces the occurrence of side reactions such as polymerization and deamination;

[0038] (2) The conversion rate of raw material MDT of the present invention reaches more than 99.9%, and the selectivity of product MACM reaches more than 98.3%, and the content of the first isomer in the MACM product is 26.7wt%.

[0039] (3) Due to the unique core-shell structure of the catalyst, the catalyst has good stability, the MACM yield reaches more than 98%, and the catalyst life is more than 2000h, which has good industrial application prospects. DETAILED DESCRIPTION

[0040] The technical solution of the present invention is further described below in conjunction with specific embodiments.

[0041] Preparation method of M@Ru / γ-Al2O3 core-shell catalyst: add alkaline metal oxide modified γ-Al2O3 carrier to ethanol-water system, fill with nitrogen for protection, then add the precursor of auxiliary agent M, add NaBH4 for reduction to obtain M / γ-Al2O3. Disperse the obtained M / γ-Al2O3 solid into aqueous solution, add ruthenium precursor, reduce with hydrazine hydrate, dry at 120℃ for 6-12h, reduce at 200-500℃ for 3-12h in fixed bed device before use, and use hydrogen volume space velocity 50-500h -1 , and obtained M@Ru / γ-Al2O3 core-shell catalyst.

[0042] The reaction of preparing MACM by continuous hydrogenation of MDT includes the following steps: the reaction is carried out in a fixed bed reactor, MDT is dissolved in a solvent tetrahydrofuran, and transported to the fixed bed reactor through a feed pump, and MDT is hydrogenated under the action of a catalyst to obtain the product MACM. The M@Ru / γ-Al2O3 core-shell catalyst, the alkaline metal oxide is one of CaO, MgO, BaO, La2O3, SrO, and the additive M is one of Mo, Mn, Co, Zn, Cr, Re. In a specific embodiment, the hydrogenation pressure is 2.0-10.0MPa, the reaction temperature is 90-220°C, and the feed mass space velocity of MDT is 0.1-1.0h -1 , the molar ratio of hydrogen to MDT is 10.0 to 80.0.

[0043] In the following test example:

[0044] The amounts of MDT, MACM, deamination products, and the first isomer were tested by gas chromatography and quantitatively analyzed using n-butanol as the internal standard;

[0045] Conversion rate of MDT = number of moles of MDT reacted / number of moles of MDT entering the reaction system * 100%;

[0046] Selectivity of MACM = moles of MACM generated / moles of MDT reacted*100%;

[0047] The yield of 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane (MACM) = the actual number of moles of MACM prepared / the theoretical number of moles of MACM that can be prepared*100%; = the conversion rate of MDT×the selectivity of MACM*100%;

[0048] Deamination product selectivity = mole number of deamination product generated / mole number of MDT reacted*100%;

[0049] The first isomer ratio = the peak area of ​​the first isomer of MACM in gas chromatography / the peak area of ​​all isomers of MACM*100%.

[0050] Example 1 Preparation of Catalyst

[0051] Weigh a certain mass of calcium nitrate tetrahydrate, dissolve it in purified water, and prepare a calcium nitrate solution (calcium ion concentration 0.5 mol / L). Weigh 50.0 g of γ-Al2O3 carrier, add it to the above calcium nitrate solution, soak it in equal volume for 24 hours, dry it at 120℃ for 4 hours, and roast it at 600℃ for 4 hours. After roasting, the mass ratio of CaO to γ-Al2O3 is 1 / 5.

[0052] 10.0g of the above-mentioned γ-Al2O3 loaded with CaO was dispersed in 60mL of ethanol-water system (volume ratio 1:1), 2.60g of cobalt nitrate hexahydrate was added, the material temperature was controlled at 50°C, 0.80g of an aqueous solution of NaBH4 with a mass concentration of 10% was added dropwise under nitrogen protection, reduction was performed for 12h, and filtration was performed to obtain Co / γ-Al2O3. The obtained solid Co / γ-Al2O3 was redispersed in 60mL of purified water, 5.06g of an aqueous solution of ruthenium trichloride with a mass concentration of 2% containing Ru was added dropwise under nitrogen protection, the temperature was raised to 80°C, 2.54g of hydrazine hydrate was added dropwise, and the temperature was kept at 80°C for 6h. Filter, wash, and dry at 110°C for 6h to obtain catalyst A1, with a Co loading of 5% and a Ru loading of 1%.

[0053] Example 2 Preparation of Catalyst

[0054] Weigh a certain amount of manganese nitrate tetrahydrate and dissolve it in purified water to prepare a manganese nitrate solution (manganese ion concentration 0.5 mol / L). Weigh 50.0g of γ-Al2O3 carrier and add it to the above manganese nitrate solution. Immerse in equal volumes for 24h, dry at 120℃ for 4h, and calcine at 600℃ for 4h. The mass ratio of MnO to γ-Al2O3 is 1 / 5.

[0055] 10.0g of the above-mentioned γ-Al2O3 loaded with MnO was dispersed in 60mL of ethanol-water system (volume ratio 1:1), 2.60g of cobalt nitrate hexahydrate was added, the material temperature was controlled at 50°C, 0.80g of NaBH4 aqueous solution with a mass concentration of 10% was added dropwise under nitrogen protection, reduced for 12h, filtered, and Co / γ-Al2O3 was obtained. The obtained solid Co / γ-Al2O3 was redispersed in 60mL of purified water, 5.06g of ruthenium trichloride aqueous solution with a mass concentration of 2% containing Ru was added dropwise under nitrogen protection, the temperature was raised to 80°C, 2.54g of hydrazine hydrate was added dropwise, and the temperature was kept at 80°C for 6h. Filter, wash, and dry at 110°C for 6h to obtain catalyst A2, with a Co loading of 5% and a Ru loading of 1%.

[0056] Example 3 Preparation of Catalyst

[0057] Weigh a certain amount of zinc nitrate hexahydrate and dissolve it in purified water to prepare a zinc nitrate solution (zinc ion concentration 0.5 mol / L). Weigh 50.0 g of γ-Al2O3 carrier and add it to the above zinc nitrate solution. Immerse in equal volumes for 24 hours, dry at 120°C for 4 hours, and calcine at 600°C for 4 hours. The mass ratio of ZnO to γ-Al2O3 is 1 / 5.

[0058] 10.0g of the above-mentioned γ-Al2O3 loaded with ZnO was dispersed in 60mL of ethanol-water system (volume ratio 1:1), 2.60g of cobalt nitrate hexahydrate was added, the material temperature was controlled at 50°C, 0.80g of an aqueous solution of NaBH4 with a mass concentration of 10% was added dropwise under nitrogen protection, reduction was performed for 12h, and filtration was performed to obtain Co / γ-Al2O3. The obtained solid Co / γ-Al2O3 was redispersed in 60mL of purified water, 5.06g of an aqueous solution of ruthenium trichloride with a mass concentration of 2% containing Ru was added dropwise under nitrogen protection, the temperature was raised to 80°C, 2.54g of hydrazine hydrate was added dropwise, and the temperature was kept at 80°C for 6h. Filter, wash, and dry at 110°C for 6h to obtain catalyst A3, with a Co loading of 5% and a Ru loading of 1%.

[0059] Example 4 Preparation of Catalyst

[0060] Weigh a certain mass of calcium nitrate tetrahydrate, dissolve it in purified water, and prepare a calcium nitrate solution (calcium ion concentration 0.5 mol / L). Weigh 50.0 g of γ-Al2O3 carrier, add it to the above calcium nitrate solution, soak it in equal volumes for 24 hours, dry it at 120℃ for 4 hours, and roast it at 600℃ for 4 hours. The mass ratio of CaO to γ-Al2O3 is 1 / 5.

[0061] 10.0g of the above-mentioned γ-Al2O3 loaded with CaO was dispersed in 60mL of ethanol-water system (volume ratio 1:1), 1.56g of cobalt nitrate hexahydrate was added, the material temperature was controlled at 50°C, 0.80g of NaBH4 aqueous solution with a mass concentration of 10% was added dropwise under nitrogen protection, reduced for 12h, filtered, and Co / γ-Al2O3 was obtained. The obtained solid Co / γ-Al2O3 was redispersed in 60mL of purified water, 5.06g of ruthenium trichloride aqueous solution with a mass concentration of 2% containing Ru was added dropwise under nitrogen protection, the temperature was raised to 80°C, 2.54g of hydrazine hydrate was added dropwise, and the temperature was kept at 80°C for 6h. Filtered, washed, and dried at 110°C for 6h to obtain catalyst A4, with a Co loading of 3% and a Ru loading of 1%.

[0062] Example 5 Preparation of Catalyst

[0063] Weigh a certain mass of calcium nitrate tetrahydrate, dissolve it in purified water, and prepare a calcium nitrate solution (calcium ion concentration 0.5 mol / L). Weigh 50.0 g of γ-Al2O3 carrier, add it to the above calcium nitrate solution, soak it in equal volumes for 24 hours, dry it at 120℃ for 4 hours, and roast it at 600℃ for 4 hours. The mass ratio of CaO to γ-Al2O3 is 1 / 5.

[0064] Disperse 10.0g of the above-mentioned γ-Al2O3 loaded with CaO in 60mL of ethanol-water system (volume ratio 1:1), add 3.59g of cobalt nitrate hexahydrate, control the material temperature at 50°C, add 0.80g of NaBH4 aqueous solution with a mass concentration of 10% dropwise under nitrogen protection, reduce for 12h, filter, and obtain Co / γ-Al2O3. The obtained solid Co / γ-Al2O3 is redispersed in 60mL of purified water, and under nitrogen protection, add 5.06g of ruthenium trichloride solution with a mass concentration of 2% containing Ru dropwise, heat to 80°C, add 2.54g of hydrazine hydrate dropwise, and keep warm at 80°C for 6h. Filter, wash, and dry at 110°C for 6h to obtain catalyst A5, with a Co loading of 7% and a Ru loading of 1%.

[0065] Example 6 Preparation of Catalyst

[0066] Weigh a certain mass of calcium nitrate tetrahydrate, dissolve it in purified water, and prepare a calcium nitrate solution (calcium ion concentration 0.5 mol / L). Weigh 50.0 g of γ-Al2O3 carrier, add it to the above calcium nitrate solution, soak it in equal volumes for 24 hours, dry it at 120℃ for 4 hours, and roast it at 600℃ for 4 hours. The mass ratio of CaO to γ-Al2O3 is 1 / 5.

[0067] 10.0g of the above-mentioned γ-Al2O3 loaded with CaO was dispersed in 60mL of ethanol-water system (volume ratio 1:1), 2.56g of cobalt nitrate hexahydrate was added, the material temperature was controlled at 50°C, 0.80g of NaBH4 aqueous solution with a mass concentration of 10% was added dropwise under nitrogen protection, reduction was performed for 12h, and filtration was performed to obtain Co / γ-Al2O3. The obtained solid Co / γ-Al2O3 was redispersed in 60mL of purified water, 10.12g of ruthenium trichloride aqueous solution with a mass concentration of 2% containing Ru was added dropwise under nitrogen protection, the temperature was raised to 80°C, 2.54g of hydrazine hydrate was added dropwise, and the temperature was kept at 80°C for 6h. Filter, wash, and dry at 110°C for 6h to obtain catalyst A6, with a Co loading of 5% and a Ru loading of 2%.

[0068] Example 7 Preparation of Catalyst

[0069] Weigh a certain mass of calcium nitrate tetrahydrate, dissolve it in purified water, and prepare a calcium nitrate solution (calcium ion concentration 0.5 mol / L). Weigh 50.0 g of γ-Al2O3 carrier, add it to the above calcium nitrate solution, soak it in equal volumes for 24 hours, dry it at 120℃ for 4 hours, and roast it at 600℃ for 4 hours. The mass ratio of CaO to γ-Al2O3 is 1 / 5.

[0070] Disperse 10.0g of the above-mentioned γ-Al2O3 loaded with CaO in 60mL of ethanol-water system (volume ratio 1:1), add 2.56g of cobalt nitrate hexahydrate, control the material temperature at 50°C, add 0.80g of 10% NaBH4 aqueous solution dropwise under nitrogen protection, reduce for 12h, filter, and obtain Co / γ-Al2O3. Disperse the obtained solid heavy Co / γ-Al2O3 in 60mL of purified water, add 2.53g of 2% Ru-containing ruthenium trichloride aqueous solution dropwise under nitrogen protection, heat to 80°C, add 2.54g of hydrazine hydrate dropwise, and keep warm at 80°C for 6h. Filter, wash, and dry at 110°C for 6h to obtain catalyst A7, with a Co loading of 5% and a Ru loading of 0.5%.

[0071] Comparative Example 1

[0072] Comparative Example A1 uses a commercial 1% Ru / Al2O3 catalyst purchased from Xi'an Kaili New Materials Co., Ltd.

[0073] Test Example 1-8

[0074] The catalyst evaluation was carried out in a fixed bed reactor. The catalyst was loaded into a reaction tube with an inner diameter of 13 mm. The loading amount is shown in Table 1.

[0075] MDT was dissolved in tetrahydrofuran solvent to obtain a raw material solution of 15 wt % MDT, and the MDT raw material solution was pumped into the fixed bed through a feed pump.

[0076] Hydrogenation reaction conditions: reaction temperature 110°C, reaction pressure 3.0MPa, MDT feed mass space velocity 0.2h -1 , the molar ratio of hydrogen to MDT is 30.0, and the evaluation results are shown in Table 1:

[0077] Table 1

[0078]

[0079] In Table 1, by comparing the test data of A1, A2, and A3, it can be seen that the catalyst activity is: auxiliary agent Co>auxiliary agent Zn>auxiliary agent Mn, and with the addition of auxiliary agent Co, the selectivity of the target product MACM is also the highest. The possible reason is that the auxiliary agent Co forms an alloy with Ru, and Co transfers electrons to Ru, which is beneficial to the activation of the benzene ring.

[0080] In Table 1, by comparing the evaluation data of A1, A4, and A5, it can be seen that the addition amount of the additive Co has a greater influence on the MDT hydrogenation reaction. When the Co loading is 3%, the MDT conversion rate is low, at 97.6%. When the Co loading is increased to 5%, MDT is close to complete conversion. Continuing to increase the Co loading, the catalyst performance has no obvious improvement. Therefore, the optimal Co loading is 5%.

[0081] In Table 1, by comparing the evaluation data of A1, A6, and A7, it can be seen that at the same amount of metal Ru, the catalyst with a 2% Ru loading has lower activity. The possible reason is that when the loading amount is high, the dispersion of metal Ru is poor. Although the 0.5% Ru catalyst has high activity, its MACM selectivity is low, only 97.8%. Therefore, the optimal loading amount of Ru is 1%.

[0082] In Table 1, by comparing the evaluation data of A1 and 1#, it can be seen that the activity and selectivity of the prepared Co@Ru / γ-Al2O3 core-shell catalyst are greatly improved compared with the commercial catalyst.

[0083] Test Example 9-18

[0084] Catalyst evaluation was carried out in a fixed bed reactor, and 5.0 g of Catalyst A1 was loaded into a reaction tube with an inner diameter of 13 mm.

[0085] MDT was dissolved in tetrahydrofuran solvent to obtain a raw material solution of 15 wt % MDT, and the MDT raw material solution was pumped into the fixed bed through a feed pump.

[0086] Hydrogenation reaction conditions: reaction temperature see Table 2, reaction pressure see Table 2, MDT feed mass space velocity 0.2h -1 , the molar ratio of hydrogen to MDT is 30.0. The evaluation results are shown in Table 2.

[0087] Table 2

[0088]

[0089] In Table 2, the comparison of test examples 9, 10 and 11 shows that the hydrogenation reaction temperature is 110°C, and the reaction effect is better. When the reaction temperature is as low as 100°C, the raw material is not completely converted, the MDT conversion rate is 96.3%, and the reaction is not thorough, so the hydrogenation effect is poor; and when the reaction temperature is as high as 120°C, due to the high temperature, there are more by-products such as deamination, so the selectivity of MACM decreases. It can be seen from Examples B1, B4, B5 and B6 that when the hydrogenation pressure is 2.0MPa, the MDT conversion rate is 98.9%, and the raw material is not completely converted; when the hydrogenation pressure is greater than 3.0MPa, the hydrogenation effect is better, the MDT conversion rate is greater than 99.9%, the MACM selectivity is greater than 96.4%, and the first isomer ratio is 24.3-26.7%. As the hydrogenation pressure increases, the MACM selectivity shows a downward trend. Therefore, the hydrogenation pressure is 3.0MPa, and the reaction effect is optimal.

[0090] In Table 2, it can be seen from Test Examples 9, 15 and 16 that the MDT feed mass space velocity affects the MDT conversion rate. The optimal MDT feed mass space velocity is 0.2h -1 .

[0091] In Table 2, it can be seen from Test Examples 9, 17 and 18 that the molar ratio of hydrogen to MDT is preferably 30.0.

[0092] Test Example 19-31

[0093] Catalyst evaluation was carried out in a fixed bed reactor, and 5.0 g of Catalyst A1 was loaded into a reaction tube with an inner diameter of 13 mm.

[0094] MDT was dissolved in tetrahydrofuran solvent to obtain a raw material solution of 15 wt % MDT, and the MDT raw material solution was pumped into the fixed bed through a feed pump.

[0095] Hydrogenation reaction conditions: reaction temperature 110 °C, reaction pressure 3.0 MPa, reaction time see Table 3 (starting from 1200 h, the temperature increased by 5 °C), MDT feed mass space velocity 0.2 h -1 , the molar ratio of hydrogen to MDT is 30.0.

[0096] The evaluation results are shown in Table 3.

[0097] Table 3

[0098]

[0099] From the data in Table 3, it can be seen that when the reaction time is 10 to 600 h, the MDT conversion rate is greater than 99.9%, the MACM selectivity has a gradual upward trend, and the deamination by-product has a downward trend. The prepared Co@Ru / γ-Al2O3 core-shell catalyst has good stability. After 2000 h of reaction, the MDT conversion rate is still maintained at 99.7%, the MACM selectivity is as high as 98.4%, the first isomer ratio is 26.8%, and the catalyst has no obvious deactivation phenomenon, indicating that the catalyst has good industrial application prospects for the hydrogenation of MDT to MACM.

[0100] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions and substitutions can be made without departing from the concept of the present invention, which should be regarded as belonging to the protection scope of the present invention.

[0101] Any numerical value mentioned in the present invention includes all values ​​increasing by one unit each time from the lowest value to the highest value if there is only an interval of two units between any minimum value and any maximum value. For example, if the amount of a component, or the value of a process variable such as temperature, pressure, time, etc. is declared to be 50-90, in this specification it means that 51-89, 52-88... and 69-71 and 70-71 are specifically listed. For non-integer values, 0.1, 0.01, 0.001 or 0.0001 can be appropriately considered as a unit. These are just some specially specified examples. In this application, in a similar manner, all possible combinations of numerical values ​​between the listed lowest and highest values ​​are considered to have been disclosed.

[0102] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein, on the contrary, the present invention can be extended to all other methods and applications with the same functions.

Claims

1. A core-shell catalyst, characterized in that: The core-shell catalyst comprises a carrier and a supporting component; The carrier is γ-Al2O3 loaded with an alkaline metal oxide; the alkaline metal oxide is one of CaO, MgO, BaO, La2O3, and SrO; The load component has metal M as a core and metal Ru as an outer shell; the metal M is selected from any one of Mo, Mn, Co, Zn, Cr, and Re.

2. The core-shell catalyst according to claim 1, characterized in that The metal M is an auxiliary agent, and the metal Ru is an active component; Preferably, the mass of the metal M is 0.5% to 10.0% of the total mass of the catalyst; Preferably, the mass of the metal Ru is 0.1% to 10.0% of the total mass of the catalyst.

3. The core-shell catalyst according to claim 1 or 2, characterized in that The mass ratio of the basic metal oxide to γ-Al2O3 is 1 / 30 to 1 / 3.

4. The method for preparing the core-shell catalyst according to any one of claims 1 to 3, comprising the steps of: in an inert atmosphere, a mixed system containing γ-Al2O3, a solvent, NaBH4 and an M precursor is subjected to a reduction reaction I to obtain M / γ-Al2O3; a dispersed system containing M / γ-Al2O3, water, a Ru precursor and hydrazine hydrate is subjected to a reduction reaction II to obtain the core-shell catalyst.

5. The method for preparing a core-shell catalyst according to claim 4, characterized in that: The solvent is a mixture of ethanol and water, and the volume ratio of ethanol to water is 1:1 to 1:10; The inert atmosphere is selected from at least one of nitrogen, argon or helium; The Ru precursor is selected from at least one of ruthenium trichloride, ruthenium acetate, and ruthenium acetylacetonate; The M precursor is at least one of nitrate or acetate.

6. The method for preparing a core-shell catalyst according to claim 4 or 5, characterized in that: The conditions of the reduction reaction I include: temperature 10-60° C., normal pressure, and reduction time 1-6 h; In terms of mass ratio, γ-Al2O3: solvent: M precursor: NaBH4 = 1: (2~8): (0.2~1.0): (0.05~0.5).

7. The method for preparing a core-shell catalyst according to claim 4, 5 or 6, characterized in that: The conditions of the reduction reaction II include: reduction temperature of 50 to 90° C., normal pressure, and reduction time of 3 to 9 hours; In terms of mass ratio, M / γ-Al2O3: water: Ru precursor: hydrazine hydrate = 1: (1-10): (0.5-3.0): (0.1-1.0).

8. The method for preparing a core-shell catalyst according to any one of claims 4 to 7, characterized in that: The method further comprises a step of drying the core-shell catalyst, wherein the drying conditions include: Drying temperature 110~150℃; drying time 6~12h; Preferably, the method further comprises the step of reducing the core-shell catalyst, and the reduction conditions include: Reduction temperature 200~500℃; reduction time 3~12h; The reducing atmosphere is hydrogen, with a volume space velocity of 50 to 500 h -1 .

9. A method for preparing MACM by continuous hydrogenation, characterized in that: 3,3'-dimethyl-4,4'-diaminophenylmethane is contacted with a catalyst to undergo a continuous hydrogenation reaction to prepare 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, wherein the catalyst is the core-shell catalyst according to any one of claims 1 to 3, or the catalyst is the core-shell catalyst obtained by the preparation method according to any one of claims 4 to 8.

10. The method according to claim 9, characterized in that The conditions for the hydrogenation reaction include: The reaction pressure is 2-10 MPa; the reaction temperature is 90-220°C; The feed mass space velocity of 3,3'-dimethyl-4,4'-diaminophenylmethane is 0.1~1.0h -1 ; The molar ratio of hydrogen to 3,3'-dimethyl-4,4'-diaminophenylmethane is 10 to 80; Preferably, the conversion rate of 3,3'-dimethyl-4,4-diaminodicyclohexylmethane is ≥94.6%, preferably ≥97.6%, preferably ≥97.8%, more preferably ≥99.9%; The selectivity of 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane is 95.4% to 98.7%; The content of the first isomer in the 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane product is 21% to 30%, preferably 21.6% to 29.8%; the first isomer of 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane has a structure shown in Formula I, The yield of 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane is 90.2% to 98.6%, preferably 92.0% to 98.5%.

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