A supercritical ammonia hydrogenation reaction catalyst and its preparation method and application

Abstract

The invention discloses a supercritical ammonia hydrogenation reaction catalyst and its preparation method and application. The preparation of the catalyst comprises the following steps: (1) mixing active metals Co, Mn, Ce and auxiliary metals uniformly, then heating and melting to obtain alloy liquid; (2) under high temperature conditions, the alloy obtained by step (1) is hydraulically pressed into the pores of a nested multilayer hollow porous SiO2 material; (3) the SiO2 material after step (2) is pressed into the alloy liquid is cooled step by step, cooled to 10-5°C, and a catalyst precursor is obtained; (4) the catalyst precursor obtained by step (3) is activated in situ to obtain the supercritical ammonia hydrogenation reaction catalyst. The catalyst has high catalytic activity and stable structure. When synthesizing 3-aminomethyl-3,5,5-trimethylcyclohexylamine under supercritical conditions, the catalyst has high selectivity, few by-products, and high cis-trans isomer ratio.

Description

Technical Field

[0001] The invention belongs to the field of catalyst preparation, and in particular relates to a supercritical ammonia hydrogenation reaction catalyst and a preparation method and application thereof. Background Art

[0002] 3-aminomethyl-3,5,5-trimethylcyclohexylamine (isophorone diamine) is mainly used as a curing agent for epoxy resins; in the production of polyurethane, it can be used as a crosslinking agent, coupling agent, hydroxyl stabilizer and special monomer, especially for the preparation of the corresponding isophorone diisocyanate (IPDI for short). In addition, 3-aminomethyl-3,5,5-trimethylcyclohexylamine can also be used as an amine component of polyamide, which is commonly known as nylon. It has good mechanical properties and wear resistance, chemical resistance, certain flame retardancy, low friction coefficient and easy processing. As an alicyclic diamine, 3-aminomethyl-3,5,5-trimethylcyclohexylamine is suitable for most reactions involving amines. Under certain specific conditions, it is suitable for reacting with ketones, aldehydes, phosgene, carboxylic acids and epoxy substances. At room temperature, 3-aminomethyl-3,5,5-trimethylcyclohexylamine can be mixed with aliphatic hydrocarbons, halogenated hydrocarbons and aromatic hydrocarbons, as well as water, esters, alcohols, ethers, etc. in any proportion. At the same time, because isophorone diamine is easy to modify, its modified products play an indispensable role in magnetic tape adhesives, adhesives for flexible packaging composite films, ink industry, as well as pesticide industry and pharmaceutical industry.

[0003] In recent years, my country's economic growth has accelerated. With the development of epoxy resin, polyurethane, polyurea and oil field related industries, the demand for 3-aminomethyl-3,5,5-trimethylcyclohexylamine has shown a rapid growth trend and is expected to continue to grow in the next few years. Therefore, how to better develop and apply 3-aminomethyl-3,5,5-trimethylcyclohexylamine will be a challenging task, and the systematic research and development of high-quality and excellent performance 3-aminomethyl-3,5,5-trimethylcyclohexylamine will surely become a hot spot in the future.

[0004] 3-aminomethyl-3,5,5-trimethylcyclohexylamine is synthesized by ammoniation and hydrogenation of isophoronenitrile (IPN for short). Hydrogenation reaction often requires the addition of catalysts. There are many types of conventional hydrogenation catalysts, mainly: ① Skeleton catalysts: Raney nickel, Raney cobalt (promoters such as Cr can be added). In the process of synthesizing 3-aminomethyl-3,5,5-trimethylcyclohexylamine by hydrazine hydrate method, Deggusa Company used Raney nickel and Raney cobalt as hydrogenation catalysts in the hydrogenation process, respectively, in which CoCl2·6H2O and NiCl2·6H2O were used as co-catalysts, respectively, and yields of 70% and 80% were obtained. The disadvantage of this method is that it is difficult to recover the catalyst and co-catalyst system; ② Supported catalyst: Supported Co, Supported Ru, Franz Merger et al. used Co catalyst (mainly Co, and 5% Mn and 3% P, each weight calculated as oxide), which has a sandy appearance of 1-1.5 mm. IPN is hydrogenated on this catalyst after imidization. The reactor uses two tubular reactors in series, and the hydrogenation conditions are 25MPa and 130°C. Finally, 97.7% of 3-aminomethyl-3,5,5-trimethylcyclohexylamine and 0.3% of bicyclic secondary amine (1,3,3-trimethyl-6-azabicyclo[3.2.1]octane) are obtained; ③ Formed fixed bed catalyst, Roland Burmeister, Thomas Hass and others used a Raney cobalt-based formed fixed bed catalyst. The preparation method of this catalyst is to mix Co-Al alloy and metal Co (as a binder), then sinter the powder mixture to form it, and then activate it by leaching with alkaline solution. The literature uses Raney Co flake particles (5 mm long, 3 mm in diameter) as a hydrogenation catalyst, TiO2 as an imidization catalyst, and the hydrogenation adopts the reaction conditions of 100°C and 6MPa. The content of 3-aminomethyl-3,5,5-trimethylcyclohexylamine in the obtained product is 92%, and the contents of bicyclic secondary amine and Amidine are 3% and 3.3% respectively; ④ Unsupported Ru-Co catalyst, when preparing the reduced Co catalyst by coprecipitation method, appropriate Ru salt can be added to prepare Ru-Co catalyst. The Ru-Co bimetallic catalyst prepared from CoCO3 by HaruhikoKusaka, Masamichi Onuki and others showed better activity than the catalyst prepared from other Co compounds.

[0005] The active components of the above catalysts are mainly transition metals of Group VI and Group VIII, which have a strong affinity for hydrogen. The most commonly used are nickel, iron, cobalt, platinum, palladium and rhodium, followed by copper, molybdenum, chromium, zinc, tungsten, etc., and their oxides or sulfides can also be used as hydrogenation catalysts. The groups hydrogenated in the second step of preparing 3-aminomethyl-3,5,5-trimethylcyclohexylamine from IPN are mainly cyano and imino groups. Ru, Co and Ni are preferred in practical applications. In order to improve the activity, selectivity and service life of the catalyst, the catalyst can contain other doped metals or other modifiers. Typical doped metals include Mo, Fe, Ag, Cr, V, Ti, Zr and Mn, as well as rare earth elements. The catalyst can also contain modifiers, mainly those substances that can affect the acidity and alkalinity of the catalyst by their own properties, such as alkaline components such as oxides and hydroxides of alkali metals and alkaline earth metals.

[0006] At present, most of the patents reported are loaded catalysts, and the commonly used carriers are SiO2, alumina, diatomaceous earth, activated carbon, etc. Patent US5286906A uses an impregnation process to load Co and Ru onto a SiO2 carrier, and suppresses the formation of the secondary amine product 1,3,3-trimethyl-6-azabicyclo[3,2,1]octane (referred to as bicyclic secondary amine) by adjusting the content of Co and Ru. However, the inhibitory effect of the catalyst on the bicyclic secondary amine is not significant, and the content of the bicyclic secondary amine is 5.7%-15.8%. In addition, a large amount of organic solvent methanol is used in the reaction process, which is not conducive to environmental protection; Patent US5371292A reports that IPN is hydrogenated on this catalyst after imidization. The reactor uses two tubular reactors in series, and the hydrogenation conditions are 25MPa and 130°C. Finally, 97.7% of 3-aminomethyl-3,5,5-trimethylcyclohexylamine and 0.3% of bicyclic secondary amine are obtained, but it does not involve and cis-trans ratio; Patent CN105032430B reports an eggshell-type Co-Ni-Fe@SiO2 catalyst prepared by chemical vapor deposition, which is used to catalyze IPN amination and hydrogenation to prepare 3-aminomethyl-3,5,5-trimethylcyclohexylamine, with high catalytic efficiency and selectivity of 3-aminomethyl-3,5,5-trimethylcyclohexylamine up to 98.8%, but the reaction tube temperature and N2 purge time in the preparation process have a great influence on the stability of the catalyst, the carrier pore volume and surface area are small, and the loading amount of active components is limited; Patent CN103664638A discloses a Ru / SiO2 catalyst, which has harsh reaction conditions and uses precious metals as active ingredients, which is costly and not conducive to industrial production. Zhou Kuo et al. prepared Co / SiO2 catalyst by sol-gel method for catalytic reaction of isophorone nitrile hydrogenation to prepare isophorone diamine, and the yield of 3-aminomethyl-3,5,5-trimethylcyclohexylamine was only 73.5%.

[0007] Supercritical ammonia hydrogenation reaction is an important direction of academic and industrial application research in recent years. Supercritical fluid (SCF) has strong solubility, good diffusion performance and is easy to control. Supercritical reaction diffuses and separates substances in a controllable manner, with significant advantages such as high reaction selectivity and few by-products, and is particularly suitable for aliphatic, alicyclic, and aromatic polyamine hydrogenation reaction systems. Using supercritical ammonia as a solvent, when supercritical conditions are reached, the fluid is completely miscible with H2, effectively eliminating the mass transfer resistance between the gas phase and the liquid phase, forming a uniform reaction solution, without the need to add additional solvent, greatly improving the reaction rate, and through the high heat exchange capacity of the supercritical ammonia system, the heat generated by the hydrogenation reaction on the catalyst surface can be removed in time, reducing the generation of hot spots and ensuring reaction selectivity. Patent CN101633610A reports a preparation method for preparing isophorone at the critical point of acetone, and no patent or literature has been retrieved for preparing isophorone diamine under supercritical ammonia conditions.

[0008] In summary, the prior art generally has the following defects: (1) The prior art uses SiO2 carrier to load transition metal to hydrogenate IPN to generate 3-aminomethyl-3,5,5-trimethylcyclohexylamine. The reported carrier pore volume and specific surface area are small, and the loading amount is small; (2) From the mechanism of synthesizing 3-aminomethyl-3,5,5-trimethylcyclohexylamine from IPN, it can be seen that the by-product bicyclic secondary amine is generated from cis-IPAN. If a high cis-trans ratio IPDA is to be obtained, the content of bicyclic secondary amine will inevitably increase. There are not many reports on the existing technology suitable for production that can simultaneously obtain a high cis-trans ratio and a low bicyclic secondary amine content; (3) The effect of the metal catalyst content on the cis-trans ratio of 3-aminomethyl-3,5,5-trimethylcyclohexylamine and the by-products is not discussed. Summary of the invention

[0009] The first problem to be solved by the present invention is to provide a supercritical ammonia hydrogenation reaction catalyst and a preparation method thereof, wherein the catalyst has high catalytic activity and strong structural stability.

[0010] The second problem to be solved by the present invention is to provide an application of the catalyst in the synthesis of 3-aminomethyl-3,5,5-trimethylcyclohexylamine (IPDA), and by combining supercritical conditions, a high time-space specific molar conversion rate, high selectivity and high cis-trans isomerization ratio are achieved, and the content of by-products is reduced.

[0011] The technical solution of the present invention is as follows:

[0012] A method for preparing a supercritical ammonia hydrogenation reaction catalyst comprises the following steps:

[0013] (1) mixing active metals Co, Mn, Ce and auxiliary metals uniformly, and then heating and melting them to obtain alloy liquid;

[0014] The auxiliary metal is an electronic auxiliary and / or a structural auxiliary;

[0015] (2) hydraulically injecting the alloy obtained in step (1) into the pores of the nested multilayer hollow porous SiO2 material;

[0016] (3) cooling the SiO2 material after being pressed into the alloy liquid in step (2) step by step to a temperature of -10 to 5° C. to obtain a catalyst precursor;

[0017] (4) in-situ activating the catalyst precursor obtained in step (3) to obtain the supercritical ammonia hydrogenation reaction catalyst.

[0018] The catalyst uses Co-Mn-Ce as the three-component metal active center, adds electronic additives and / or structural additives, and uses nested multilayer hollow porous SiO2 as a carrier. Based on the unique multilayer hollow structure of the catalyst and the addition of specific performance additives, the catalyst has higher catalytic activity and stronger structural stability.

[0019] In addition, experiments have found that regulating the content of any two or three metals in the catalyst can regulate the ratio of cis-trans isomers of alicyclic diamines and reduce the content of by-product bicyclic secondary amines. Preferably, the active metal content (based on the amount of added metal elements) is: 50% to 60% Co, 20% to 35% Mn, and 5% to 10% Ce, based on the total metal weight.

[0020] The additive itself has no activity or very little activity, but adding it to the catalyst can change the chemical composition, chemical structure, ion valence, acidity and alkalinity, lattice structure, surface structure, dispersion state, mechanical strength, etc. of the catalyst, thereby improving the activity, selectivity, stability and life of the catalyst. According to different mechanisms of action, additives are generally divided into two categories: structural type and electronic type. Preferably, the additive metal is two or three of Zr, Mo, and Ti. The present invention adds Zr as a structural additive to enhance the mechanical strength of the catalyst. Mo is an electronic additive with a d% of 43%, which has fewer d-band holes than Co and Mn. When the catalyst is formed, d electrons flow from Mo to Co / Mn, and the hydrogenation activity is enhanced. Preferably, in step (1), the content of the additive metal is: 1-3% Zr, 1-3% Mo, and 0.3-0.8% Ti by total metal weight.

[0021] Preferably, in step (1), the heating and melting temperature is 1800-2000°C.

[0022] Preferably, in step (2), the specific surface area of ​​the SiO2 material is 950 to 1050 m 2 / g, pore volume is 1.0~1.2cm 3 / g; as a further preferred embodiment, the specific surface area is 990m 2 / g, pore volume 1.1cm 3 / g.

[0023] Preferably, in step (4), the in-situ activation is carried out in an environment with an ammonia concentration of 25-28 wt %, and the feed space velocity of the ammonia is 1-5 h -1 ; The activation temperature is 50-90℃, and the activation time is 50-150min.

[0024] The invention also provides a supercritical ammonia hydrogenation reaction catalyst obtained by the preparation method.

[0025] The present invention also provides a method for preparing 3-aminomethyl-3,5,5-trimethylcyclohexylamine, comprising:

[0026] Under the action of the supercritical ammonia hydrogenation reaction catalyst, isophoronenitrile imine undergoes a hydrogenation reaction under supercritical conditions of liquid ammonia to obtain the 3-aminomethyl-3,5,5-trimethylcyclohexylamine.

[0027] The method utilizes supercritical fluid to improve reaction rate and selectivity advantage, supercritical ammonia is introduced into the hydrogenation of isophorone nitrile imine, alkaline conditions reduce catalyst hydrocyanic acid poisoning risk, improve catalyst stability and lifespan, and expect to reach high space-time specific molar conversion.But prior art (such as patent CN104119233B) reports, removes ammonia in reaction system (excess ammonia may increase byproduct bicyclic secondary amine content), can improve the concentration of amino nitrile, reduce the content of byproduct bicyclic secondary amine, therefore, prior art is difficult to take into account high space-time specific molar conversion and low bicyclic secondary amine content these two purposes simultaneously.The inventor finds that when adopting novel catalyst of the present invention, can play synergistic effect with supercritical system, while ensuring efficient hydrogenation, reducing the content of byproduct, ensure high space-time specific molar conversion of hydrogenation, low byproduct bicyclic secondary amine bicyclic secondary amine content. The catalyst space-time processing capacity (referring to the molar amount of isophoronenitrile imine processed per unit volume of catalyst per unit time) is 0.5-5 mol / (L*h), the IPDA selectivity is more than 98%, the reaction cis-trans ratio reaches 4.25, and the content of bicyclic secondary amine is less than 1%. Moreover, the catalyst was investigated for more than 3000 hours, and no significant decrease in activity was found, which provides a reference for industrial production.

[0028] Preferably, the hydrogenation reaction is carried out in two fixed bed reactors connected in series, the supercritical ammonia hydrogenation reaction catalyst is placed in the two fixed bed reactors, and the isophoronenitrile imine, liquid ammonia and hydrogen are respectively and continuously introduced into the first fixed bed reactor.

[0029] Preferably, the mass ratio of liquid ammonia to isophoronenitrile imine is 1:1-100:1, the molar ratio of hydrogen to isophoronenitrile imine is 3:1-200:1, and the catalyst space-time processing capacity is 0.5-5 mol / (L*h).

[0030] The hydrogenation reaction is carried out in the first fixed bed reactor at a low temperature, with a reaction temperature of 50-100° C. and a pressure of 12-35 MPa; and in the second fixed bed reactor at a high temperature, with a reaction temperature of 110-180° C. and a reaction pressure of 12-35 MPa.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] (1) The catalyst used in the present invention is a novel composite catalyst material with three-component metal catalysis, which is a nested multilayer hollow porous SiO2 material (specific surface area 990m 2 / g, pore volume 1.1cm 3 / g) as a carrier, Co-Mn-Ce as an active component, and Zr, Mo, and Ti as additives. The supported catalyst has a high mass transfer rate and significantly improves the reaction rate and conversion rate.

[0033] (2) The amino group in cis-IPAN nucleophilically attacks the cyano group to form a byproduct amidine, which is hydrogenated to form a bicyclic secondary amine. Therefore, a high cis-trans ratio will inevitably lead to the formation of a high content of byproduct bicyclic secondary amine. The novel composite catalyst material of the present invention controls the content of any two or three metals in the catalyst to make the reaction have a high cis-trans ratio and a low bicyclic secondary amine content. The cis-trans ratio reaches more than 3, the bicyclic secondary amine content is less than 1.0%, and the space-time processing capacity of the catalyst is 0.5-5 mol / (L*h);

[0034] (3) The catalyst disclosed in the present invention performs a hydrogenation reaction under supercritical conditions of liquid ammonia, and no additional reaction solvent needs to be added. The alkaline environment reduces the risk of hydrogen cyanide poisoning. When the supercritical condition is reached, hydrogen with extremely low solubility in organic solvents is completely miscible with the supercritical fluid, and the mass transfer resistance between the gas phase and the liquid phase is eliminated, which greatly improves the reaction rate. At the same time, the high heat exchange capacity of the supercritical ammonia system can timely remove the heat generated by the hydrogenation reaction on the catalyst surface, reduce the generation of hot spots, and ensure the reaction selectivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is the process of forming bicyclic secondary amines. DETAILED DESCRIPTION

[0036] Bicyclic secondary amine is a high-boiling-point compound (boiling point is 266.2°C). When heated at high temperature with IPDA, it is easy to cause the bicyclic secondary amine after ring opening to form a polymer with IPDA or the amino group of IPDA will attack the CNC bond structure in the bicyclic secondary amine to form an unstable intermediate. At this time, the intermediate may decompose into bicyclic secondary amine and NH3. During the continuous heating process, the content of bicyclic secondary amine increases. When the high-temperature mixed liquid is quenched, the polymer formed by the bicyclic secondary amine after ring opening and IPDA suddenly increases, causing the mixed liquid to wax, making it difficult to separate IPDA and bicyclic secondary amine in the distillation stage. In the product after distillation, bicyclic secondary amine accounts for more than 70% of the impurities.

[0037] Figure 1 The formation process of bicyclic secondary amine is:

[0038] Depend on Figure 1 It can be seen that the generation of cis-IPDA and Amindine (amidine for short) from cis-IPAN is a competitive process. The amino group in cis-IPAN undergoes nucleophilic addition to the cyano group to generate the byproduct amidine. The amidine generates the byproduct bicyclic secondary amine under hydrogen reduction conditions. The side reaction path can be interfered with from the following ideas: (1) Use a highly active catalyst to increase the hydrogenation rate and reduce the nucleophilic reaction of the amino group to the cyano group. The catalyst can change the rate of a chemical reaction. The catalyst temporarily intervenes in the reaction and builds a new pathway between the initial and final states of the reaction system, thereby changing the energy state pathway of the reaction and allowing the reaction to proceed along a more labor-saving pathway. The use of a highly active catalyst can increase the cis-trans ratio of the product and reduce the generation of the byproduct bicyclic secondary amine. (2) Use supercritical ammonia as a solvent to enhance the solvent alkalinity, affect the electronic effect of the cyano group in cis-IPAN, and reduce the rate of nucleophilic addition.

[0039] Based on the above ideas, the present invention uses Co-Mn-Ce as active metals, metal Zr, Mo, Ti as additives, and nested multilayer hollow porous SiO2 as a carrier to prepare a three-component high-activity hydrogenation catalyst. Valence bond theory believes that transition metal atoms are combined with hybrid orbitals, and the percentage d% of d atomic orbitals in the hybrid orbitals is a characteristic parameter related to the catalytic activity and other physical properties of the metal. The larger the d% of the metal, the more electrons are filled in the corresponding d energy band, and the fewer d holes. For metal hydrogenation catalysts, d% has a better hydrogen adsorption capacity between 40% and 50%. The present invention selects metal hydrogenation catalysts Co and Mn with d%=40, adds rare earth metal Ce, and obtains a three-component active metal catalytic center. The doping of Ce can enhance the dispersibility of Mn-Co on the carrier surface and increase the redox sites, thereby enhancing the hydrogenation capacity.

[0040] The present invention utilizes supercritical fluid to improve reaction rate and selectivity advantage, introduces supercritical amine into hydrogenation reaction, and expects to achieve high space-time specific molar conversion rate, but patent CN104119233B reports that removing ammonia in the reaction system (excess ammonia may increase the content of by-product bicyclic secondary amine) can increase the concentration of aminonitrile and reduce the content of by-product bicyclic secondary amine. Therefore, in order to achieve high space-time specific molar conversion rate and low bicyclic secondary amine content at the same time, the present invention develops a novel catalyst, which reduces the content of by-products while ensuring efficient hydrogenation, plays a synergistic role with the supercritical system, and ensures high space-time specific molar conversion rate and low bicyclic secondary amine content of hydrogenation reaction. The catalyst space-time processing capacity is 0.5-5mol / (L*h), IPDA selectivity is more than 98%, the reaction cis-trans ratio reaches 4.25, and the bicyclic secondary amine content is less than 1%.

[0041] The third edition of Industrial Catalysis (by Huang Zhongtao) states that the activity of the catalyst is closely related to the surface area, thermal stability and mechanical strength of the carrier. 2 / g, pore volume 1.1cm 3 / g) as the carrier, and does not exclude the feasibility of other mesoporous carriers, with Co-Mn-Ce as the active component and Zr, Mo and Ti as additives.

[0042] Experiments have found that by adjusting the content of any two or three active metals in the three-component catalyst, the ratio of IPDA cis-trans isomers can be adjusted while reducing the content of byproduct bicyclic secondary amines. At the same time, the present invention uses supercritical ammonia as a solvent, and does not require the addition of additional organic solvents such as methanol, which reduces the risk of hydrocyanic acid poisoning and is beneficial to environmental protection. By optimizing the active metal content, reaction temperature and reaction pressure in the catalyst, the IPDA selectivity in the hydrogenation reaction is above 98%, the reaction cis-trans ratio is as high as 4.25, the bicyclic secondary amine content is below 1%, and the catalyst space-time processing capacity is 0.5 to 5 mol / (L*h). 。

[0043] The three-component active metal catalyst described in this patent is a new type of composite catalyst, the active components are composed of metal Co, Mn, and Ce, with a nested multilayer hollow porous SiO2 material as a carrier (specific preparation reference: Template synthesis of nested multilayer hollow porous SiO2 materials and research on their adsorption activity, Li Gang et al., "Guangdong Chemical Industry", 2019, 46(24): 14-15), and two or three of Zr, Mo, and Ti are added as additives, preferably three additives.

[0044] The supercritical conditions are: T=110-180°C, P=12-35MPa, preferably 150°C, 30MPa.

[0045] The catalyst contains 50% to 60% Co, 20% to 35% Mn, 5% to 10% Ce based on the total metal content, and the additive content is 1 to 3% Zr, 1 to 3% Mo, and 0.3 to 0.8% Ti. The preferred content is 55 to 60% Co, 23 to 27% Mn, 6 to 9% Ce, 1 to 3% Zr, 1 to 3% Mo, and 0.3 to 0.8% Ti.

[0046] The two fixed bed reactors are connected in series, the first fixed bed reactor performs a low-temperature hydrogenation reaction at a reaction temperature of 50-100°C and a pressure of 12-35MPa; the second fixed bed reactor performs a high-temperature hydrogenation reaction at a reaction temperature of 110-180°C and a reaction pressure of 12-35MPa.

[0047] Catalyst Preparation Example

[0048] (1) Weigh 300 g of metal Co, 132 g of metal Mn, 44 g of metal Ce, 12 g of metal Zr, 12 g of metal Mo, and 3 g of metal Ti, put the weighed metals into a graphite crucible of a medium frequency melting furnace and mix them, replace the furnace cavity of the medium frequency melting furnace with nitrogen, turn on the heating switch of the A heating system and the circulating cooling water, adjust the heating power opening to 40%, heat the metal mixture (1800-2000°C) and maintain it for 4 minutes to obtain an alloy liquid;

[0049] (2) At this time, 1512g of the prepared nested multilayer hollow porous SiO2 material is weighed and placed in a high-temperature resistant sealable container, and the heating switch of the B heating system is turned on to raise the temperature of the high-temperature resistant sealable container to about 1100°C. The alloy liquid is then poured into the high-temperature resistant sealable container. The sealing cover of the high-temperature resistant sealable container can be slowly pressed down to the limit position through the control rod above the medium frequency furnace cavity, and then lifted and pressed down again. This is repeated 5 times, so that the alloy liquid is pressed into the pores of the SiO2 material.

[0050] (3) Pour the SiO2 material with alloy liquid pressed into the high-temperature resistant sealable container into the rotating disc below, with the disc rotating at a speed of 20r / min. Turn off the two heating systems A and B, and the SiO2 material falls into the cooling chamber, where it is cooled to 800°C in 27 minutes and maintained for 4 hours; then cooled to 0°C in 5 minutes. Then put the cooled SiO2 material into the shaping machine for shaping for 60 minutes to obtain the catalyst precursor.

[0051] (4) 200 g of the prepared catalyst precursor was loaded into a high-pressure hydrogenation fixed-bed reaction tube (inner diameter 30 mm) and activated in an environment of 25 wt% ammonia water. The feed space velocity of ammonia water was 3 h -1The activation temperature was 70°C and the activation time was 90 min. The metal content of the catalyst after activation was 59.6% Co-26.2% Mn-8.7% Ce-2.4% Zr-2.4% Mo-0.6% Ti.

[0052] The amount of metal used can be adjusted and catalysts with other ratios can be obtained using a similar method as described above.

[0053] Example 1

[0054] A two-stage series reactor is used, 300 mL of catalyst is added to the first hydrogenation reactor, 200 mL of catalyst (metal content is 59.6% Co-26.2% Mn-8.7% Ce-2.4% Zr-2.4% Mo-0.6% Ti) is added to the second hydrogenation reactor, the feed of isophorone nitrile imine is 369 g / h, the feed amount of liquid ammonia is 1500 g / h, entering from the top of the hydrogenation reactor, and the feed amount of H2 is 201 L / h entering from the top. The product is collected in a collection container below the reactor. The catalyst space-time processing capacity corresponding to this operating condition is 4.5 mol / (L*h), the first stage is a low-temperature hydrogenation reaction, the reaction temperature is 100°C, and the pressure is 15 MPa; the second stage reaction is a high-temperature hydrogenation reaction, the reaction temperature is 165°C, and the reaction pressure is 30 MPa. After the system ran stably for 100 hours, the product was sampled for GC analysis. The content of the raw material isophoronenitrile imine was less than 1%, the content of the main by-product bicyclic secondary amine was 0.98%, the IPDA selectivity was 98.4%, and the cis-trans isomer ratio was 4.25.

[0055] Embodiment 2-6

[0056] The main difference from Example 1 is that the three active metal contents of the catalyst are different.

[0057]

[0058]

[0059] Embodiment 7-9

[0060] The main difference from Example 1 is the temperature of the hydrogenation high temperature section.

[0061]

[0062] Examples 10-12

[0063] The main difference from Example 1 is the pressure in the high temperature section of hydrogenation.

[0064]

[0065] Comparative Examples 1-4

[0066] The main difference from Example 1 is that the active metal of the catalyst is different.

[0067]

[0068] Comparative Example 5

[0069] The difference from Example 1 is that methanol is used as the solvent and the catalyst space-time processing capacity is 0.1 mol / (L*h).

[0070]

[0071] Embodiment 13

[0072] According to the method of Example 1, the system was stably operated for 3000 hours, and the results of the catalyst inspection showed that the selectivity of IPDA was still above 98%, the cis-trans ratio was 3.7, and the content of bicyclic secondary amine was 0.9%.

Claims

1. A method for preparing a supercritical ammonia hydrogenation catalyst, characterized in that: The following steps are involved: (1) Active metals Co, Mn, Ce and auxiliary metals are mixed uniformly, and then heated and melted to obtain alloy liquid; The auxiliary metal is an electronic auxiliary and / or a structural auxiliary; (2) hydraulically injecting the alloy obtained in step (1) into the pores of the nested multilayer hollow porous SiO2 material; (3) cooling the SiO2 material after being pressed into the alloy liquid in step (2) step by step to a temperature of -10 to 5° C. to obtain a catalyst precursor; (4) in-situ activating the catalyst precursor obtained in step (3) to obtain the supercritical ammonia hydrogenation reaction catalyst; In step (1), the active metal content is 50% to 60% Co, 20% to 35% Mn, and 5% to 10% Ce, based on the total metal weight; In step (1), the auxiliary metal is two or three of Zr, Mo and Ti; In step (4), the in-situ activation is carried out in an environment with an ammonia concentration of 25-28 wt %, and the feed space velocity of the ammonia is 1-5 h -1 ; The activation temperature is 50-90℃, and the activation time is 50-150min.

2. The method for preparing a supercritical ammonia hydrogenation catalyst according to claim 1, wherein: In step (1), based on the total metal weight, the content of the auxiliary metal is: 1-3% Zr, 1-3% Mo, and 0.3-0.8% Ti.

3. The preparation method of supercritical ammonia hydrogenation catalyst according to claim 1, characterized in that: In step (2), the specific surface area of ​​the SiO2 material is 950 to 1050 m 2 / g, pore volume is 1.0~1.2cm 3 / g.

4. A supercritical ammonia hydrogenation catalyst obtained by the preparation method according to any one of claims 1 to 3.

5. A method for preparing 3-aminomethyl-3,5,5-trimethylcyclohexylamine, characterized in that: include: Under the action of the supercritical ammonia hydrogenation reaction catalyst as claimed in claim 4, isophoronenitrile imine undergoes a hydrogenation reaction under supercritical conditions of liquid ammonia to obtain the 3-aminomethyl-3,5,5-trimethylcyclohexylamine.

6. The method for preparing 3-aminomethyl-3,5,5-trimethylcyclohexylamine according to claim 5, characterized in that: The hydrogenation reaction is carried out in two fixed bed reactors connected in series, the supercritical ammonia hydrogenation reaction catalyst is placed in the two fixed bed reactors, and the isophoronenitrile imine, liquid ammonia and hydrogen are respectively and continuously introduced into the first fixed bed reactor.

7. The method for preparing 3-aminomethyl-3,5,5-trimethylcyclohexylamine according to claim 5, characterized in that: The mass ratio of liquid ammonia to isophoronenitrile imine is 1:1-100:1, the molar ratio of hydrogen to isophoronenitrile imine is 3:1-200:1, and the space-time processing capacity of the catalyst is 0.5-5 mol / (L*h).

8. The method for preparing 3-aminomethyl-3,5,5-trimethylcyclohexylamine according to claim 6 or 7, characterized in that: The hydrogenation reaction is carried out in a first fixed bed reactor at a low temperature, with a reaction temperature of 50 to 100° C. and a pressure of 12 to 35 MPa; A high-temperature hydrogenation reaction is carried out in the second fixed bed reactor, the reaction temperature is 110-180°C, and the reaction pressure is 12-35MPa.

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