Catalyst and method for preparing same, method for preparing cyclohexylamine compounds

Abstract

The application relates to a catalyst and a preparation method thereof, and a preparation method of a cyclohexylamine compound. The catalyst comprises a carrier and an active component loaded on the carrier, and the active component comprises a ruthenium metal element, a tungsten metal element and a cobalt metal element.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of catalytic synthesis, in particular to a catalyst, a preparation method thereof and a preparation method of cyclohexylamine compounds. BACKGROUND

[0002] Cyclohexylamine compounds such as methylcyclohexanediamine are a class of alicyclic amines, which are widely used in rubber auxiliaries, plastics, papermaking, textiles and other fields, and are important fine chemical intermediates. For example, methylcyclohexanediamine is an important raw material for synthesizing methylcyclohexane diisocyanate, which has good anti-yellowing and aging resistance, and is an important raw material for preparing high-grade coatings, adhesives and waterborne polyurethanes. For example, the polyurethane product prepared by using methylcyclohexane diisocyanate is more stable in air and is not easy to yellow, and is widely used in various fields.

[0003] With the wide application of polyurethane products in various fields, the demand for aliphatic isocyanates such as methylcyclohexane diisocyanate is increasing, and thus the demand for synthetic raw materials such as alicyclic diamines is also increasingly urgent and continues to rise. In the traditional technology, aniline compounds are often selectively hydrogenated to synthesize aliphatic cyclohexylamine compounds, but there are still problems such as low conversion rate, poor selectivity and small yield in mass production.

[0004] Therefore, the traditional technology still needs to be improved. SUMMARY

[0005] Therefore, it is necessary to provide a catalyst, a preparation method thereof and a preparation method of cyclohexylamine compounds, aiming to improve the conversion rate and selectivity of cyclohexylamine compounds.

[0006] In a first aspect of the present application, a catalyst is provided, which comprises a carrier and an active component supported on the carrier, and the active component comprises a ruthenium metal element, a tungsten metal element and a cobalt metal element.

[0007] In the above-mentioned catalyst, the carrier is loaded with a specific active component, which comprises a ruthenium metal element, a tungsten metal element and a cobalt metal element. Through the synergistic effect of the specific type of multi-metallic catalytically active component, a higher active catalytically active site is provided, and at the same time, the catalytic activity of each part of the catalyst tends to be uniform. When the catalyst is applied to prepare methylcyclohexanediamine and other cyclohexylamine compounds by hydrogenation reaction, the catalytic activity and selectivity are high, and the yield of methylcyclohexanediamine and other cyclohexylamine compounds can be improved.

[0008] In particular, when the catalyst is applied to prepare methylcyclohexanediamine and other cyclohexylamine compounds by hydrogenation reaction, even in large-scale production, high catalytic activity and selectivity can be maintained, and the yield of methylcyclohexanediamine and other cyclohexylamine compounds in mass production can be improved.

[0009] In some embodiments, the catalyst satisfies at least one of the following conditions (1) to (3):

[0010] (1) In the catalyst, the mass proportion of the ruthenium metal element is 1% to 11%;

[0011] (2) In the catalyst, the mass proportion of the tungsten metal element is 0.5% to 5%;

[0012] (2) In the catalyst, the mass proportion of the cobalt metal element is 0.5% to 5%.

[0013] Further regulate the mass ratio of each component in the active components of the catalyst to further enhance the synergistic effect between the components and improve the catalytic activity and selectivity.

[0014] In some embodiments, the catalyst satisfies at least one of the following conditions (4) to (6):

[0015] (4) In the catalyst, the mass proportion of the ruthenium metal element is 3% to 8%;

[0016] (5) In the catalyst, the mass proportion of the tungsten metal element is 1% to 3%;

[0017] (6) In the catalyst, the mass proportion of the cobalt metal element is 1% to 3%.

[0018] In some embodiments, the component of the carrier includes at least one of γ-Al2O3, diatomaceous earth and activated carbon.

[0019] In some embodiments, the component of the support includes γ-Al2O3 modified with rare earth metal elements.

[0020] The rare earth metal-modified γ-Al2O3 contains rare earth metals, which can further promote catalysis. When this catalyst is used to prepare cyclohexylamine compounds such as methylcyclohexanediamine through hydrogenation reaction, it can inhibit the shedding of amino groups in the reaction substrate and delay the deactivation of the catalyst, thereby improving the yield while increasing the stability of the catalyst and extending the service life of the catalyst.

[0021] In some embodiments, the mass ratio of the rare earth metal element to the γ-Al2O3 is (0.01-0.08):1.

[0022] In a second aspect of the present application, a method for preparing the catalyst of the first aspect is provided, comprising the following steps:

[0023] The carrier and the active slurry are mixed and then impregnated and sintered in sequence to prepare a preform;

[0024] subjecting the preform to a reduction reaction to produce the catalyst;

[0025] The components of the active slurry include a ruthenium-containing salt compound, a tungsten-containing salt compound, and a cobalt-containing salt compound.

[0026] In a third aspect of the present application, a preparation method of a cyclohexylamine compound is provided, including the following steps:

[0027] Under the action of the catalyst of the first aspect, a cyclohexylamine compound represented by formula (B) is prepared by subjecting compound (A) to a hydrogenation reaction with hydrogen:

[0028]

[0029] wherein n1 and n2 are integers, n1≥2, n2≥1, and n1+n2≤6.

[0030] R1 is independently selected from a linear alkyl group having 1-5 carbon atoms.

[0031] In the preparation method of the cyclohexylamine compound, the above catalyst is used, and the catalytic activity and selectivity are high, which can improve the yield of cyclohexylamine compounds such as methylcyclohexanediamine. Even in large-scale production, high catalytic activity and selectivity can be maintained, and the yield of cyclohexylamine compounds such as methylcyclohexanediamine can be improved.

[0032] In some embodiments, the hydrogenation reaction satisfies at least one of the following conditions (7)-(10):

[0033] (7) the hydrogenation reaction is carried out at 130-190°C;

[0034] (8) during the hydrogenation reaction, the space velocity of the catalyst is 0.3-1.1 h -1 -1.1 h -1

[0035] By adjusting the conditions of the hydrogenation reaction, the yield can be further improved, especially the yield in mass production.

[0036] (9) the molar ratio of the compound (A) to the hydrogen is 1:(3-10);

[0037] (10) R1 is selected from methyl, n1 is 2, and n2 is 1.

[0038] In some embodiments, the hydrogenation reaction is sequentially carried out in a first reactor and a second reactor connected in series, and the first reactor and the second reactor are both filled with the catalyst, and the method specifically includes the following steps:

[0039] ​The compound (A) and the hydrogen gas are introduced into the primary reactor to perform a primary hydrogenation reaction;

[0040] The material in the primary reactor after the primary hydrogenation reaction is introduced into the secondary reactor to perform a secondary hydrogenation reaction;

[0041] The primary reactor and the secondary reactor are both connected with low-temperature hot water through a cold hydrogen pipeline to control the temperature of the catalyst bed in the reactor. BRIEF DESCRIPTION OF DRAWINGS

[0042] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The accompanying drawings are included to provide a better understanding of the preferred embodiments and are incorporated in and constitute a part of this application. Moreover, in the drawings, like reference numerals refer to corresponding parts throughout the several views.

[0043] Figure 1 is a process flow chart for preparing methylcyclohexanediamine in an embodiment;

[0044] BRIEF DESCRIPTION OF DRAWINGS

[0045] 1, mixed raw material tank; 2, hydrogenation feed pump; 3, raw material heater; 4, primary feed mixer; 5, primary reactor; 6, secondary feed mixer; 7, secondary reactor; 8, cooler; 9, separator; 10, circulating pressure pump. DETAILED DESCRIPTION

[0046] The present application is further described in connection with the following specific examples. The present application can be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and fully convey the scope of the application to those skilled in the art.

[0047] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0048] The term "alkyl" in the present application refers to an alkane group formed by removing one hydrogen from an alkane, wherein the carbon atoms are connected by carbon-carbon single bonds and the remaining valence bonds are all combined with hydrogen, including straight-chain alkyl groups and branched-chain alkyl groups. Similarly, the term "alkyl group having 1-5 carbon atoms" in the present application can have 1-5 carbon atoms, including 1, 2, 3, 4, and 5, and refers to an alkane group having 1-5 carbon atoms, non-limiting examples of which include methyl, ethyl, propyl, and the like.

[0049] In the present application, a single bond connected to a substituent group runs through the corresponding ring, indicating that the substituent group can be connected to any connectable position of the ring, for example, In the present application, R can be connected to any substitutable position of the benzene ring.

[0050] The hydrogenation reaction generally needs to be carried out in a hydrogenation catalyst. Many catalysts with high catalytic activity have been developed in the traditional technology, but they still cannot meet the increasing industrial demand. In particular, catalysts that exhibit excellent catalytic efficiency in the laboratory-scale trace experiment stage still need to improve the yield in the mass production process.

[0051] This is because the preparation process of an organic compound is a complex chemical reaction process, and from the laboratory-scale trace experiment to the large-scale industrial production process, there are a large number of unpredictable technical bottlenecks due to the "scale-up effect". Many preparation conditions or condition factors cannot be accurately controlled and simulated in the experimental stage, or some conditions may develop in an uncontrollable direction after scaling up, which is difficult to predict.

[0052] In summary, in the traditional technology, toluene amine is often selectively hydrogenated to synthesize aliphatic cyclohexylamine compounds, but in mass production, there are still problems such as low conversion rate, poor selectivity, and small yield.

[0053] Based on this, the technical personnel of the present application have provided the catalyst and its preparation method, and the preparation method of cyclohexylamine compounds in the present application after a large amount of creative exploration.

[0054] In an embodiment of the present application, a catalyst is provided, which comprises a carrier and an active component supported on the carrier, and the active component comprises a ruthenium metal element, a tungsten metal element, and a cobalt metal element.

[0055] In the above catalyst, the specific active component is loaded on the carrier, including a ruthenium metal element, a tungsten metal element and a cobalt metal element, through the synergistic effect of specific types of multi-metallic catalytically active components, the catalytically active sites with better activity are provided, and the catalytic activity of the catalyst is uniform. When the catalyst is applied to the preparation of cyclohexylamine compounds such as methylcyclohexanediamine by a hydrogenation reaction, the catalytic activity and selectivity are high, and the yield of cyclohexylamine compounds such as methylcyclohexanediamine can be improved.

[0056] It can be understood that the above-mentioned "active component loaded on the carrier" can be loaded on the surface of the carrier and / or the inside of the carrier.

[0057] It should be noted that in the above catalyst, the ruthenium metal element mainly exists in the form of a ruthenium metal element, and other valence state ruthenium metal ions may also exist, but will not negatively affect the overall catalytic activity of the catalyst; optionally, the mass fraction of the ruthenium metal element is ≥50% based on the total mass; further optionally, the mass fraction of the ruthenium metal element is ≥60%; further optionally, the mass fraction of the ruthenium metal element is ≥70%; further optionally, the mass fraction of the ruthenium metal element is ≥80%; further optionally, the mass fraction of the ruthenium metal element is ≥90%.

[0058] Similarly, the tungsten metal element mainly exists in the form of a tungsten metal element, and the cobalt metal element mainly exists in the form of a cobalt metal element.

[0059] Optionally, the mass fraction of the tungsten metal element is ≥50% based on the total mass; further optionally, the mass fraction of the tungsten metal element is ≥60%; further optionally, the mass fraction of the tungsten metal element is ≥70%; further optionally, the mass fraction of the tungsten metal element is ≥80%; further optionally, the mass fraction of the tungsten metal element is ≥90%.

[0060] Optionally, the mass fraction of the cobalt metal element is ≥50% based on the total mass; further optionally, the mass fraction of the cobalt metal element is ≥60%; further optionally, the mass fraction of the cobalt metal element is ≥70%; further optionally, the mass fraction of the cobalt metal element is ≥80%; further optionally, the mass fraction of the cobalt metal element is ≥90%.

[0061] In some embodiments, the above-mentioned catalyst is a hydrogenation reaction catalyst.

[0062] Optionally, the above-mentioned hydrogenation reaction is a hydrogenation reaction for preparing methylcyclohexanediamine from toluenediamine.

[0063] In some embodiments, in the catalyst, the mass fraction of the ruthenium metal element is 1% to 11%.

[0064] In some embodiments, the mass percentage of the ruthenium metal element in the catalyst is 1% to 10%.

[0065] In some embodiments, the mass percentage of the ruthenium metal element in the catalyst is 3% to 8%.

[0066] In some embodiments, the mass percentage of the tungsten metal element in the catalyst is 0.5% to 5%.

[0067] In some embodiments, the mass percentage of the tungsten metal element in the catalyst is 1% to 5%.

[0068] In some embodiments, the mass percentage of the tungsten metal element in the catalyst is 1% to 3%.

[0069] In some embodiments, the mass percentage of the cobalt metal element in the catalyst is 0.5% to 5%.

[0070] In some embodiments, the mass percentage of the cobalt metal element in the catalyst is 1% to 5%.

[0071] In some embodiments, the mass percentage of the cobalt metal element in the catalyst is 1% to 3%.

[0072] Further, the mass percentages of the components in the active component of the catalyst are further adjusted to further improve the synergistic effect between the components, and improve the catalytic activity and selectivity.

[0073] In the above "1% to 11%", the mass percentage of the ruthenium metal element includes the minimum value and the maximum value of the range, and every value between the minimum value and the maximum value, specific examples include but are not limited to the point values in the embodiments and the following point values: 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%; or a range composed of any two numerical values, for example, can be "2% to 11%, 3% to 11%, 4% to 11%, 5% to 11%, 6% to 11%, 7% to 11%, 8% to 11%, 9% to 11%, 10% to 11%, 1% to 10%, 2% to 10%, 3% to 10%, 4% to 10%, 5% to 10%, 6% to 10%, 7% to 10%, 8% to 10%, 9% to 10%, 1% to 9%, 2% to 9%, 3% to 9%, 4% to 9%, 5% to 9%, 6% to 9%, 7% to 9%, 8% to 9%, 1% to 8%, 2% to 8%, 3% to 8%, 4% to 8%, 5% to 8%, 6% to 8%, 7% to 8%, 1% to 5%, 2% to 5%, 3% to 5%, 4% to 5%, 1% to 4%, 2% to 4%, 3% to 4%.

[0074] In the above-mentioned "0.5% to 5%", the mass ratio of tungsten metal elements or cobalt metal elements includes the minimum value and the maximum value of the range, and each value between the minimum value and the maximum value, and specific examples include but are not limited to the following point values: 0.5%, 1%, 2%, 3%, 4%, 5%; or a range composed of any two numerical values, for example, 1% to 5%, 2% to 5%, 3% to 5%, 4% to 5%, 0.5% to 4%, 1% to 4%, 2% to 3%, 3% to 4%, 0.5% to 3%, 1% to 3%, 2% to 3%.

[0075] In some embodiments, the components of the carrier include at least one of γ-Al2O3, diatomite and activated carbon.

[0076] In some embodiments, the components of the carrier include γ-Al2O3 modified by a rare earth metal element.

[0077] The γ-Al2O3 modified by a rare earth metal element contains rare earth metals and γ-Al2O3, which can further assist catalysis. When the catalyst is applied to the preparation of cyclohexylamine compounds such as methylcyclohexanediamine by hydrogenation reaction, it can inhibit the loss of amine groups in the substrate and delay the deactivation of the catalyst, thereby improving the yield while improving the stability of the catalyst and prolonging the service life of the catalyst.

[0078] In some embodiments, the mass ratio of the rare earth metal element to γ-Al2O3 is (0.01-0.08):1.

[0079] In some embodiments, the rare earth metal element includes at least one of lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), scandium (Sc) and yttrium (Y).

[0080] In some embodiments, the rare earth metal element includes cerium (Ce).

[0081] It should be noted that in the catalyst product, in the above-mentioned γ-Al2O3 modified by a rare earth metal element, the form of the rare earth metal element includes but is not limited to ionic form and elemental form, which can be mixed.

[0082] In some embodiments, the preparation of the γ-Al2O3 modified by a rare earth metal element includes the following steps:

[0083] Mixing and aging the precursor of γ-Al2O3 and the salt compound of the rare earth metal to prepare a mixed precursor.

[0084] The mixed precursor is subjected to a first calcination treatment and a second calcination treatment in sequence to prepare the γ-Al2O3 modified by the rare earth metal.

[0085] The first calcination treatment is performed under a protective gas, and the second calcination treatment is performed under an oxygen-containing atmosphere.

[0086] In some embodiments, the protective gas comprises at least one of nitrogen and an inert gas; further, the inert gas comprises at least one of helium, neon, argon, krypton, and xenon.

[0087] In some embodiments, the oxygen-containing atmosphere can be a pure oxygen atmosphere or air.

[0088] After the second calcination treatment, the rare earth metal element is converted into a rare earth metal oxide, and further, a reduction reaction is performed when an active component is subsequently loaded, and part of the rare earth metal element is not excluded from being converted into a rare earth metal element, but does not hinder the overall effect of the carrier.

[0089] In some embodiments, the first calcination treatment is performed at a temperature of 500-1200°C for 1-4 hours.

[0090] In some embodiments, the second calcination treatment is performed at a temperature of 500-900°C for 1-4 hours.

[0091] In some embodiments, after the step of mixing and aging, and before the step of the first calcination treatment, a step of drying the mixed precursor is further included.

[0092] The mixed precursor is subjected to a first calcination treatment and a second calcination treatment in sequence to prepare the γ-Al2O3 modified by the rare earth metal.

[0093] In some embodiments, the precursor of γ-Al2O3 comprises boehmite.

[0094] In some embodiments, the salt compound of the rare earth metal comprises at least one of a halide salt of the rare earth metal, a sulfate salt of the rare earth metal, an ammonium salt of the rare earth metal, and a nitrate salt of the rare earth metal.

[0095] It can be understood that the amount of boehmite and the salt compound of the rare earth metal is adjusted according to the mass ratio of the rare earth metal and γ-Al2O3 to be finally obtained.

[0096] In some embodiments, the step of mixing and aging is performed in water, and specifically comprises the following steps:

[0097] The precursor of γ-Al2O3 is mixed with water to prepare a sol, the salt compound of the rare earth metal is added, and the mixture is subjected to an aging treatment at 15-35°C for 10-24 hours.

[0098] In some embodiments, the mass percentage of the precursor of γ-Al2O3 in the sol is 10% to 30%.

[0099] In some embodiments, the particle size of the catalyst is (0.5-2) x (5-15) mm.

[0100] In another embodiment of the present application, a method for preparing the catalyst is provided, comprising steps S10-S20.

[0101] In step S10, the carrier and the active slurry are mixed, and then subjected to impregnation treatment and sintering treatment to prepare a preform.

[0102] In step S20, the preform is subjected to reduction reaction to prepare the catalyst.

[0103] In some embodiments, the components of the active slurry further include a solvent, and the solvent includes water.

[0104] In some embodiments, the components of the active slurry further include a solvent, and the solvent includes water.

[0105] In some embodiments, the components of the active slurry further include a solvent, and the solvent includes water.

[0106] In some embodiments, the solid content of the active slurry is 0.5% to 5%.

[0107] In some embodiments, the impregnation treatment is performed at room temperature, specifically at 15°C to 35°C.

[0108] In some embodiments, the sintering treatment is performed at a temperature of 400°C to 500°C for 2h to 8h.

[0109] In some embodiments, after the step of impregnation treatment and before the step of sintering treatment, the following step is further included:

[0110] In the mixture after the impregnation treatment, an alkali compound is added to make the system alkaline, and then dried.

[0111] In some embodiments, in the mixture after the impregnation treatment, an alkali compound is added to make the pH value of the system 8 to 10.

[0112] Optionally, the alkali compound includes at least one of hydroxides of alkali metals and carbonates of alkali metals.

[0113] In some embodiments, the carbonate of alkali metal includes at least one of normal salt M2CO3, acid salt MHCO3 and hydroxide carbonate M2(OH)2CO3 of alkali metal.

[0114] M is alkali metal; optionally, the alkali metal includes at least one of lithium, sodium and potassium.

[0115] In some embodiments, the alkali compound includes sodium hydroxide.

[0116] In some embodiments, the alkali compound is added in the form of aqueous solution of alkali; further, the mass concentration of the alkali compound is 20% to 45%.

[0117] In some embodiments, the drying is performed under vacuum; further, the temperature of drying is 100℃, and the time is 4h.

[0118] In some embodiments, the sintering is performed under vacuum; further, the sintering temperature is 400℃ to 500℃, and the time is 2h to 8h.

[0119] In some embodiments, the sintering temperature is 450℃, and the time is 5h.

[0120] In some embodiments, the reduction reaction is performed under the action of reducing gas; optionally, the reducing gas includes hydrogen.

[0121] In some embodiments, the temperature of the reduction reaction is 200℃ to 300℃, and the time is 2h to 8h.

[0122] In some embodiments, the temperature of the reduction reaction is 250℃, and the time is 5h.

[0123] In some embodiments, after the reduction reaction, the method further includes the following steps:

[0124] The product of the reduction reaction is placed in an aqueous alkali solution for standing treatment, and then filtered and dried.

[0125] In some embodiments, the standing treatment is performed for 15h to 25h; further, the standing treatment is performed at room temperature, specifically, 15℃ to 35℃.

[0126] In some embodiments, the aqueous alkali solution contains an alkali compound; further, in the aqueous alkali solution, the mass concentration of the alkali compound is 20% to 45%.

[0127] The type of the alkali compound is selected according to the above description, and will not be repeated here.

[0128] In some embodiments, the mass ratio of the base compound to the carrier in the catalyst is (0.05-2): 1.

[0129] Another embodiment of the present application provides a method for preparing a cyclohexylamine compound, comprising the following step S30:

[0130] Step S30, under the action of the above-mentioned catalyst, compound (A) is subjected to hydrogenation reaction with hydrogen to prepare a cyclohexylamine compound represented by formula (B):

[0131]

[0132] wherein n1 and n2 are integers, n1≥2, n2≥1, and n1+n2≤6.

[0133] R1 is independently selected at each occurrence from a linear alkyl group having 1-5 carbon atoms.

[0134] The method for preparing the cyclohexylamine compound described above is carried out using the catalyst described above, which has high catalytic activity and selectivity, and can improve the yield of cyclohexylamine compounds such as methylcyclohexanediamine. Even in large-scale production, high catalytic activity and selectivity can be maintained, and the yield of cyclohexylamine compounds such as methylcyclohexanediamine can be improved.

[0135] It can be understood that when n2≥2, multiple R1 can be the same or different.

[0136] In some embodiments, n1=2 and n2=1.

[0137] In some embodiments, R1 is independently selected at each occurrence from any one of a methyl group and an ethyl group.

[0138] In some embodiments, compound (A) has the following structure:

[0139]

[0140] In some embodiments, R1 is a methyl group.

[0141] In some embodiments, compound (A) comprises a toluenediamine.

[0142] Alternatively, the toluenediamine comprises at least one of 2,5-toluenediamine, 2,4-toluenediamine, and 2,6-toluenediamine.

[0143] In some embodiments, the hydrogenation reaction is a liquid-phase hydrogenation reaction.

[0144] In some embodiments, the hydrogenation reaction is carried out at 130-190°C.

[0145] In some embodiments, the space velocity of the catalyst during the hydrogenation reaction is 0.3h -1 ~ 1.1h -1 .

[0146] In some embodiments, the space velocity of the catalyst during the hydrogenation reaction is 0.5h -1 ~ 1h -1 .

[0147] The space velocity of the catalyst refers to the volume of the raw material compound (A) treated per unit volume of the catalyst per unit time.

[0148] By adjusting the conditions of the hydrogenation reaction, the yield is further improved, especially the yield in mass production.

[0149] In some embodiments, the molar ratio of the compound (A) to hydrogen is 1 : (3 ~ 10). In some embodiments, the above hydrogenation reaction is sequentially carried out in a primary reactor and a secondary reactor connected in series, both the primary reactor and the secondary reactor are filled with catalysts, and specifically comprising the following steps:

[0150] The compound (A) and the hydrogen are introduced into the primary reactor to carry out a primary hydrogenation reaction.

[0151] The material after the primary hydrogenation reaction in the primary reactor is introduced into the secondary reactor to carry out a secondary hydrogenation reaction.

[0152] In this way, the reaction can be further completed.

[0153] In some embodiments, the temperature of the primary hydrogenation reaction is 150°C ~ 190°C.

[0154] In some embodiments, the temperature of the secondary hydrogenation reaction is 160°C ~ 190°C.

[0155] In some embodiments, the reaction pressure of the above primary hydrogenation reaction and secondary hydrogenation reaction is independently selected from 8MPa-8.8MPa.

[0156] In other words, the pressure in the primary reactor and the secondary reactor is maintained at 8MPa-8.8MPa.

[0157] Specifically, the pressure in the primary reactor and the secondary reactor is mainly caused by the introduction of hydrogen and raw materials, and the pressure in the reactor changes with the amount and rate of the introduction of hydrogen and raw materials.

[0158] In some embodiments, the above primary reactor and secondary reactor are both column reactors.

[0159] The reactor adopts a shell-and-tube reactor, and the catalyst is evenly loaded in the shell and tube reactor. The shell-and-tube reactor can effectively improve the reaction efficiency, improve the heat transfer between the reactants and the heat-conducting medium, and the multi-stage segmented series temperature control reaction effectively improves the use efficiency of the catalyst, saves the amount of catalyst used, and at the same time makes the reaction more complete and effectively reduces the occurrence of side reactions.

[0160] In some embodiments, the shell side of the reactor is cooled by circulating low-temperature hot water to control the bed temperature, effectively preventing damage to the equipment due to overheating, protecting the equipment and extending its service life.

[0161] In some embodiments, the step of introducing compound (A) and hydrogen into the primary reactor is carried out in a continuous feeding manner to achieve continuous mass production.

[0162] In some embodiments, after the hydrogenation step, the following steps are further included:

[0163] The product of the hydrogenation reaction is sequentially subjected to water washing, deammoniation treatment and distillation treatment.

[0164] In this way, by-product impurities are further removed to obtain cyclohexylamine compounds with higher purity.

[0165] In some embodiments, the hydrogenation reaction is carried out in a solvent; further, the solvent includes tetrahydrofuran.

[0166] Furthermore, before the hydrogenation step, the method further comprises the following steps: mixing the compound (A) with a solvent and filtering.

[0167] Compound (A) is mixed with a solvent to dissolve the compound (A) in the solvent, and insoluble impurities are removed by filtration.

[0168] Optionally, insoluble solid particles with a particle size greater than 25 μm are removed by filtration.

[0169] Please refer to the Figure 1 , Figure 1 This is a process flow chart for preparing methylcyclohexanediamine in one embodiment. Specifically, taking compound (A) as toluene diamine TDA and solvent as tetrahydrofuran THF as an example, TDA and THF are transported to a mixing tank ( Figure 1 (not shown) and stirred to dissolve TDA in THF solvent. The mixed raw materials were passed through a pressure pump ( Figure 1 (not shown) is pressurized and enters the filter ( Figure 1 The insoluble solid particles with a particle size greater than 25-50 μm are filtered out and then enter the mixed raw material tank 1. The hydrogenation feed pump 2 pressurizes the raw material into the raw material heater 3 and heats it to 130℃~180℃. Figure 1The new hydrogen delivered (not shown) is mixed in the first feed mixer 4, enters the top of the first reactor 5, which is filled with the above-mentioned catalyst, and undergoes the first hydrogenation reaction under the action of the catalyst. The bed temperature of the first reactor 5 is controlled at 150-190°C by the circulation amount of low-temperature hot water and the cold hydrogen in the middle part of the reactor. After the first hydrogenation reaction, the reaction product exits the bottom of the first reactor 5, enters the second feed mixer 6, is mixed with hydrogen, and then enters the second reactor 7. The second reactor 7 is filled with the above-mentioned catalyst, and the bed temperature of the second reactor 7 is controlled at 160-190°C by the circulation amount of low-temperature hot water and the cold hydrogen in the middle part of the reactor. The top of the first reactor 5 and the top of the second reactor 7 are both provided with a cold hydrogen pipeline, which is used in combination with the low-temperature hot water to control the catalyst bed temperature in the reactor and prevent the reactor from overheating. After the second hydrogenation reaction, the reaction product is cooled to 30-50°C by the cooler 8, and then enters the separator 9 for gas-liquid phase separation. The low-pressure gas is collected at the top, and the liquid phase is further collected at the bottom and then enters a fractionation system (not shown). Figure 1

[0170] Further, the unreacted liquid phase product after the second hydrogenation reaction re-enters the first reactor 5 for hydrogenation reaction through the circulation pressure pump 10.

[0171] Further, the mass control of the liquid phase product after the second hydrogenation reaction circulating to the first reactor 5 is 45%-55% of the mass of the raw material feed directly delivered to the first reactor.

[0172] In the above process, the liquid phase hydrogenation technology is adopted, and the hydrogen circulation system is not provided in the reaction part, and a sufficient amount of hydrogen is dissolved in the circulating liquid phase product to meet the needs of the hydrogenation reaction. Compared with the gas phase hydrogenation, the hydrogen circulation system, the high-pressure separation system and the corresponding equipment are omitted, which can greatly save the investment and energy consumption. At the same time, the liquid phase hydrogenation process can eliminate the influence of the wetting factor of the catalyst, and the specific heat capacity of the circulating oil is large, thereby improving the utilization efficiency of the catalyst.

[0173] In some embodiments, the low-pressure gas and the liquid phase product of the hydrogenation reaction are heated and then enter the light-removing column. The gas phase at the top of the column after cutting enters the water washing column to remove ammonia, and the reaction product and the solvent at the bottom of the column enter the recovery column. The column is cut, and the light components are cooled by the recovery column top condenser and then enter the reflux tank at the top of the recovery column. The non-condensable gas in the reflux tank is discharged to the venting main pipe, and the light component solvent in the reflux tank is pressurized by the reflux pump at the top of the recovery column, and then part of it is returned to the top of the recovery column as reflux, and part of it is extracted to the pervaporation membrane dehydration equipment. After the solvent tetrahydrofuran is completely dehydrated, it is returned to the solvent tank for circulation. The bottom of the recovery column is heated by the reboiler, and the heating medium is low-pressure steam. The heavy component oil at the bottom of the recovery column is pressurized by the recovery column bottom pump and then used as the feed of the rectifying column. ​

[0174] The heavy component oil at the bottom of the recovery column is recycled into the rectification column, the light component at the top of the column after cutting is cooled in the condenser at the top of the rectification column after heating, and then is sent to the reflux tank at the top of the rectification column, the non-condensable gas in the reflux tank is sent to the venting main pipe, and the light component methylcyclohexylamine in the reflux tank is pressurized by the reflux pump at the top of the rectification column, and then a part of it is returned to the reflux of the rectification column, and a part of it is extracted to the methylcyclohexylamine tank for storage, so as to continuously rectify in a cycle to obtain the methylcyclohexylamine product.

[0175] Further, the hydrogen tail gas at the top of the light removal column is sent to the water washing column to remove the ammonia in the tail gas, the tail gas after removing the ammonia is sent to the water adsorption column for dehydration treatment, the dehydrated tail gas is sent to the new hydrogen liquid tank for further dehydration, and the refined hydrogen is pressurized by the new hydrogen compressor and sent to the hydrogenation reaction system for continuous recycling.

[0176] The aqueous solvent recovered from the reflux tank at the top of the solvent recovery column and the reflux tank at the top of the rectification column is sent to the membrane dehydration device, the membrane dehydration device is provided with a permeation gasification inorganic membrane, in the dehydration process of the permeation gasification inorganic membrane, the aqueous solvent is preheated and then sent to the feed side of the membrane assembly, and the permeation side is maintained in a low pressure environment by vacuumizing. On the feed side, water molecules are preferentially adsorbed on the membrane surface, and are pushed through the membrane by the water vapor pressure difference on both sides of the membrane, and are gasified into water vapor on the permeation side of the membrane. After separation operation, the anhydrous solvent tetrahydrofuran at the outlet of the membrane feed side is transported to the solvent tank, and the components on the permeation side are condensed and then treated as waste water. In this way, the recovered solvent is recycled for use.

[0177] The application will be described below in conjunction with specific examples, but the application is not limited to the following examples, and it should be understood that the appended claims generalize the scope of the application, and those skilled in the art should realize that certain changes made to the embodiments of the application will be covered by the spirit and scope of the claims of the application.

[0178] The following are specific examples

[0179] Example 1

[0180] 1. Preparation of catalyst

[0181] (1) Preparation of carrier:

[0182] A certain amount of boehmite powder is dispersed in deionized water, the mass concentration of boehmite is 20%, and stirring is performed for 1 hour to prepare a boehmite sol; cerium nitrate is added to the boehmite sol, aging is performed at room temperature for 10 hours, then drying is performed at 100-150°C for 10 hours, then calcination is performed at 1000°C for 2 hours in a nitrogen atmosphere, and then calcination is performed at 700°C for 2 hours in an air atmosphere, to obtain a rare earth metal modified alumina carrier, which is a long strip in the shape of a shamrock, and the particle size is Φ(0.5-2)×(5-15)mm, wherein, the mass ratio of the rare earth metal to the alumina in the alumina carrier is 0.05:1, which is measured by an elemental analyzer (EA).

[0183] (2) 100g of the rare earth metal modified alumina carrier is weighed, dissolved in a mixed aqueous solution containing a certain amount of ruthenium chloride, cobalt nitrate and ammonium tungstate, immersed at room temperature for 20 hours, and then a sodium hydroxide aqueous solution (32wt%) is added to adjust the pH value to 10, and then vacuum drying is performed at 100°C for 4 hours.

[0184] The dried product is calcined at 450°C for 5 hours, and then hydrogen reduction is performed at 250°C for 5 hours, and then the reduced product is placed in a 32wt% NaOH aqueous solution, the mass ratio of sodium hydroxide in the NaOH aqueous solution to the alumina carrier is 0.5:1, and then after standing for 20 hours, the solid product is obtained by filtration and vacuum drying at 100°C to obtain the catalyst.

[0185] The elemental analyzer (EA) is used for testing, and in the catalyst, the mass proportion of Ru metal is 6%, the mass proportion of W metal is 3%, and the mass proportion of Co metal is 2%, and the catalyst is recorded as: 6% Ru-3% W-3% Co / γ-Al2O3.

[0186] The physical property parameters of the catalyst are tested, and the specific method is as follows:

[0187] The bulk density of the catalyst is tested by the following method:

[0188] 50g of the catalyst is taken into a 100ml measuring cylinder, the measuring cylinder is fixed on the tap density instrument, vibration is started, and vibration is performed for 200 times until the volume does not change, and then the measuring cylinder is taken out and the value is read to obtain the volume of the catalyst.

[0189] The bulk density = the mass of the catalyst / the volume of the catalyst.

[0190] The mechanical strength, specific surface area and pore volume of the catalyst are detected by a third-party testing institution: Shanghai Fuda Testing Technology Co., Ltd., and the specific methods are as follows:

[0191] The measurement method of the mechanical strength of the catalyst: a single particle compression strength detector is used, which is a special instrument for measuring the single particle compression strength of superhard abrasive and ordinary abrasive, and this method belongs to a static measurement method.

[0192] The specific steps are as follows:

[0193] 1. Place the particles to be tested between two parallel planes, with as few contact points as possible.

[0194] 2. Apply a constant rate of increasing pressure to the particles until they break.

[0195] 3. Record the pressure value at which the particles break, which is the compressive strength of the particles.

[0196] 4. Repeat the above steps to measure multiple particles and calculate the average and standard deviation.

[0197] The specific parameters are shown in Table 1.

[0198] The specific parameters are shown in Table 1.

[0199] 2. Preparation of methylcyclohexanediamine

[0200] The specific process is shown in Figure 1 At 30-40℃ and normal pressure, 10kg of toluenediamine is dissolved in 40kg of tetrahydrofuran, filtered to obtain a raw material solution and transported to a mixed raw material tank 1. After pressurization to 6.0-9.0MPa by a hydrogenation feed pump 2, the raw material solution is sent to a raw material heater 3 at a rate of 50kg / h, heated to 140-180℃, then mixed with the transported new hydrogen in a first-stage feed mixer 4, wherein the hydrogen is sent to the first-stage feed mixer 4 at a rate of 10.56m3 / h, and the molar ratio of toluenediamine to hydrogen is 1:5.78, then transported into a first-stage reactor 5, with the inlet temperature controlled at 140-150℃. The first-stage reactor 5 is filled with the above-mentioned catalyst, and the catalyst loading is 7.94L. The reactor shell is cooled with 60℃ hot water, and the outlet temperature of the first-stage reactor 5 is controlled at 150-160℃, and the pressure of the first-stage reactor is controlled at 8.5-8.8MPa.

[0201] After the first stage of hydrogenation reaction, the reaction product is discharged from the bottom of the first stage reactor 5 into the second stage feed mixer 6, mixed with hydrogen and then fed into the second stage reactor 7, the inlet temperature of which is controlled at 150-160°C, the catalyst loading of which is 7.94L, and the outlet temperature of which is controlled at 160-180°C, the reactor shell is cooled by hot water at 60°C, and the pressure of the second stage reactor is controlled at 8.2-8.5MPa. After the second stage of hydrogenation reaction, the reaction product is cooled to 30-50°C by the cooler 8 and then separated into gas and liquid phases in the separator 9, the low pressure gas is collected from the top, and the liquid phase is further fed into the fractionation system to obtain methylcyclohexane diamine. The unreacted raw material is recycled by the circulating pressure pump 10 at a rate of 25kg / h to the first stage reactor 5 for hydrogenation reaction.

[0202] wherein the toluene diamine comprises 2,4-toluene diamine and 2,6-toluene diamine at a mass ratio of 8:2, and the methylcyclohexane diamine prepared comprises 2,4-HTDA and 2,6-HTDA. The first stage reactor 5 and the second stage reactor 7 are both fixed bed tube reactor, and the tube specification is Φ30mmx6mm, and the tube is arranged in a regular triangle.

[0203] 3. The total conversion rate of toluene diamine is calculated according to the following formula:

[0204] Total conversion rate = (total mass of toluene diamine raw material - mass of unreacted toluene diamine) / total mass of toluene diamine raw material x 100%

[0205] The selectivity of the hydrogenation reaction to methylcyclohexane diamine is calculated according to the following formula:

[0206] Selectivity = mass of methylcyclohexane diamine / mass of all products x 100%

[0207] The specific results are shown in Table 2.

[0208] Example 2

[0209] Example 2 is basically the same as Example 1, except that in the preparation of methylcyclohexane diamine in step 2, the inlet temperature of the first stage reactor 5 is controlled at 145-155°C, the catalyst loading is 6.61L, the outlet temperature of the first stage reactor 5 is controlled at 155-165°C; the inlet temperature of the second stage reactor 7 is controlled at 155-165°C, the catalyst loading is 6.61L, and the outlet temperature of the first stage reactor 7 is controlled at 155-165°C.

[0210] The other steps and process conditions are the same as those in Example 1, and the specific parameters and test results are shown in Table 2.

[0211] Example 3

[0212] Example 3 is basically the same as Example 1, except that in the preparation of methylcyclohexane diamine in Step 2, the inlet temperature of the primary reactor 5 is controlled at 150-160℃, the catalyst loading is 5.67L, and the outlet temperature of the primary reactor 5 is controlled at 160-170℃; the inlet temperature of the secondary reactor 7 is controlled at 160-170℃, the catalyst loading is 5.67L, and the outlet temperature of the primary reactor 7 is controlled at 170-190℃.

[0213] The other steps and process conditions are the same as those in Example 1, and the specific parameters and test results are shown in Table 2.

[0214] Example 4

[0215] Example 4 is basically the same as Example 1, except that in the preparation of methylcyclohexane diamine in Step 2, the inlet temperature of the primary reactor 5 is controlled at 155-165℃, the catalyst loading is 4.96L, and the outlet temperature of the primary reactor 5 is controlled at 165-170℃; the inlet temperature of the secondary reactor 7 is controlled at 165-170℃, the catalyst loading is 4.96L, and the outlet temperature of the primary reactor 7 is controlled at 175-185℃.

[0216] The other steps and process conditions are the same as those in Example 1, and the specific parameters and test results are shown in Table 2.

[0217] Example 5

[0218] Example 5 is basically the same as Example 1, except that in the preparation of methylcyclohexane diamine in Step 2, the inlet temperature of the primary reactor 5 is controlled at 160-170℃, the catalyst loading is 4.41L, and the outlet temperature of the primary reactor 5 is controlled at 165-170℃; the inlet temperature of the secondary reactor 7 is controlled at 170-180℃, the catalyst loading is 4.41L, and the outlet temperature of the primary reactor 7 is controlled at 180-190℃.

[0219] The other steps and process conditions are the same as those in Example 1, and the specific parameters and test results are shown in Table 2.

[0220] Examples 6-9

[0221] Examples 6-9 are basically the same as Example 1, except that in the preparation of the catalyst in Step 1, the amounts of ruthenium chloride, cobalt nitrate and ammonium tungstate are adjusted so that the proportion of Ru metal, the proportion of W metal or the mass proportion of Co metal in the prepared catalyst is different from that in Example 1, as shown in Table 1.

[0222] The other steps and process conditions are the same as those in Example 1, and the specific parameters and test results are shown in Table 2.

[0223] Example 10

[0224] Example 10 is substantially the same as Example 1 except that in the preparation of the catalyst in Step 1, no cerium nitrate is added in the preparation of the support.

[0225] The other steps and process conditions are the same as those in Example 1. The specific parameters and test results are shown in Table 1 and Table 2.

[0226] Comparative Example 1

[0227] Comparative Example 1 is substantially the same as Example 1 except that in the preparation of the catalyst in Step 1, the ruthenium chloride is replaced by rhodium chloride. The specific parameters are shown in Table 1.

[0228] The other steps and process conditions are the same as those in Example 1. The specific parameters and test results are shown in Table 2.

[0229] Comparative Example 2

[0230] Comparative Example 1 is substantially the same as Example 1 except that in the preparation of the catalyst in Step 1, the ruthenium chloride is replaced by rhodium chloride, and the ammonium tungstate is replaced by palladium chloride. The specific parameters of the catalyst prepared are shown in Table 1.

[0231] The other steps and process conditions are the same as those in Example 1. The specific parameters and test results are shown in Table 2.

[0232] Comparative Example 3

[0233] Comparative Example 1 is substantially the same as Example 1 except that in the preparation of the catalyst in Step 1, the ruthenium chloride is replaced by rhodium chloride, and the ammonium tungstate is replaced by platinum chloride. The specific parameters of the catalyst prepared are shown in Table 1.

[0234] The other steps and process conditions are the same as those in Example 1. The specific parameters and test results are shown in Table 2.

[0235] Comparative Example 4

[0236] Comparative Example 1 is substantially the same as Example 1 except that in the preparation of the catalyst in Step 2, no ammonium tungstate is added. The specific parameters of the catalyst prepared are shown in Table 1.

[0237] The other steps and process conditions are the same as those in Example 1. The specific parameters and test results are shown in Table 2.

[0238] The types of catalysts used in each example and comparative example and their related physical parameters are shown in Table 1.

[0239] Table 1

[0240]

[0241]

[0242]

[0243] The relevant condition parameters and calculation results in the preparation of methylcyclohexanediamine in each example and comparative example are shown in Table 2.

[0244] Table 2

[0245]

[0246]

[0247] Wherein, the catalyst space velocity refers to the volume of raw material treated by unit volume of catalyst per unit time, and the specific calculation formula is as follows:

[0248] Space velocity = total feed amount of raw material at the inlet of the first reactor (m 3 / h) / total loading volume of catalyst (m 3 )

[0249] Wherein, the raw material is toluenediamine, the density is calculated according to 1.26 g / cm 3 , the total feed amount of toluenediamine at the inlet of the first reactor is calculated according to 10 Kg / m 3 , and the total loading volume of catalyst is the sum of the total volume of catalyst loaded in the first reactor 5 and the second reactor 7.

[0250] The specific numerical value of the space velocity recorded in Table 1 is an integer obtained by rounding off the result of the above calculation formula to the decimal point.

[0251] Analyzing the data in Table 2: from the comparison of the data of Example 1 and Comparative Examples 1-4, it can be seen that when continuously producing in a large scale, under the condition that other reaction conditions are the same, when the active component of the catalyst is changed from ruthenium to rhodium, or the active component of the catalyst is changed from ruthenium to rhodium and tungsten to palladium, or the active component of the catalyst is changed from ruthenium to rhodium and tungsten to palladium, or the active component of the catalyst is changed from ruthenium to rhodium and tungsten to platinum, the conversion rate and catalyst selectivity of the reaction are all greatly reduced; further, from the data of Example 1 and Comparative Example 4, it can be seen that when the active component of the catalyst is changed from ruthenium, tungsten and cobalt to ruthenium and cobalt, the conversion rate and catalyst selectivity of the reaction are also greatly reduced.

[0252] This demonstrates that the synergistic effect of specific multimetallic catalytically active components in this application provides more and more highly active catalytic sites while also making the catalytic active sites uniform across the catalyst, resulting in high product selectivity. When used in the hydrogenation reaction to prepare cyclohexylamines such as methylcyclohexanediamine, this catalyst exhibits high catalytic activity and selectivity, significantly increasing the yield of cyclohexylamines such as methylcyclohexanediamine.

[0253] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0254] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that a person skilled in the art may make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be determined by the appended claims, and the specification and drawings may be used to interpret the claims.

Claims

1. A catalyst for catalytic hydrogenation to produce cyclohexylamine compounds, characterized in that: The catalyst comprises a carrier and an active component supported on the carrier, the active component comprising a ruthenium metal element, a tungsten metal element and a cobalt metal element; in the catalyst, the mass percentage of the ruthenium metal element is 3% to 8%; in the catalyst, the mass percentage of the tungsten metal element is 1% to 3%; and in the catalyst, the mass percentage of the cobalt metal element is 1% to 3%.

2. The catalyst of claim 1, wherein The component of the carrier comprises at least one of γ-Al2O3, diatomite and activated carbon.

3. The catalyst of claim 1, wherein The component of the carrier comprises γ-Al2O3 modified by a rare earth metal element.

4. The catalyst of claim 3, wherein In the carrier, the mass ratio of the rare earth metal element to the γ-Al2O3 is (0.01 to 0.08):

1.

5. The process for producing a catalyst according to any one of claims 1 to 4, characterized by, The method comprises the following steps: After mixing the carrier and an active slurry, the carrier is subjected to impregnation treatment and sintering treatment in sequence to prepare a preform; The preform is subjected to a reduction reaction to prepare the catalyst; The component of the active slurry comprises a ruthenium-containing salt compound, a tungsten-containing salt compound and a cobalt-containing salt compound.

6. A method for preparing cyclohexylamine compounds, characterized in that: The method comprises the following steps Under the action of the catalyst as claimed in any one of claims 1 to 4, a compound (A) is subjected to a hydrogenation reaction with hydrogen to prepare a cyclohexylamine compound as shown in formula (B); wherein n1 and n2 are both integers, n1≥2, n2≥1, and n1+n2≤6; R1 is independently selected at each occurrence from a chain alkyl group having 1 to 5 carbon atoms.

7. The method for preparing cyclohexylamine compounds as claimed in claim 6, wherein The hydrogenation reaction satisfies at least one of the following conditions (1) to (4): (1) the hydrogenation reaction is carried out at 130°C to 190°C; (2) in the hydrogenation reaction process, the space velocity of the catalyst is 0.3h -1 ~ 1.1 h -1 ; (3) the molar ratio of the compound (A) to the hydrogen is 1:(3 to 100); (4) R1 is selected from a methyl group, n1 is 2, and n2 is 1.

8. The process for the preparation of cyclohexylamine compounds according to any one of claims 6 to 7, characterized in that, The hydrogenation reaction is carried out in a primary reactor and a secondary reactor in sequence, the primary reactor and the secondary reactor both being filled with the catalyst, and the method comprises the following steps: The compound (A) and the hydrogen are introduced into the primary reactor to carry out a primary hydrogenation reaction; The material after the primary hydrogenation reaction in the primary reactor is introduced into the secondary reactor to carry out a secondary hydrogenation reaction; The primary reactor and the secondary reactor are both controlled in temperature of the catalyst bed by a cold hydrogen pipeline combined with low-temperature hot water.

9. The method for preparing cyclohexylamine compounds as claimed in claim 8, wherein The temperature of the primary hydrogenation reaction is 150°C to 190°C.

10. The method for preparing cyclohexylamine compounds according to claim 8, wherein The temperature of the secondary hydrogenation reaction is 160°C to 190°C.

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