A forming method of Ru-based catalyst for catalytic hydrogenation of 2,4-dinitrotoluene to prepare 1-methyl-2,4-cyclohexanediamine

Abstract

The present invention discloses a method for forming a Ru-based catalyst for catalytic hydrogenation of 2,4-dinitrotoluene to prepare 1-methyl-2,4-cyclohexanediamine. The method is to uniformly mix a first catalyst precursor, a second catalyst precursor, and a binder to obtain a mixed powder; then add an adhesive, stir until it becomes a gel, and then perform extrusion molding, cutting, drying, calcination, and hydrogen reduction to obtain a formed Ru-based catalyst; the first catalyst precursor is one of Ru2(CO3)3 / support, Ru2(CO3)3-Rh2(CO3)3 / support; the second catalyst precursor is RuO x / support, RuO x -RhO x / support. The present invention uses the first catalyst precursor to replace the traditional extrusion aid, talc powder. Both the first catalyst precursor and the second catalyst precursor contain metals Rh and Rh. The formed Ru-Rh alloy can improve the catalyst stability and reaction activity, and has excellent mechanical strength, high compressive strength and good wear resistance, which can meet the requirements of the industrial application scenario of hydrogenating 2,4-DNT to 2,4-HTDA.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and specifically relates to a method for forming an Ru-based catalyst for catalytic hydrogenation of 2,4-dinitrotoluene to prepare 1-methyl-2,4-cyclohexanediamine. Background Art

[0002] Supported solid catalysts are commonly used "chip" materials in the current industrial catalysis field, and catalyst forming is a prerequisite for their industrial application. Generally, the forming methods of supported solid catalysts include extrusion forming, tableting forming, spray forming, rotary forming, etc.

[0003] 1-Methyl-2,4-cyclohexanediamine (2,4-HTDA) is an important organic compound, mainly used for the production of high-end epoxy resin curing agents, which can endow epoxy resins with good mechanical properties, corrosion resistance and heat resistance, and can also be used for the synthesis of polyamide resins; in the pharmaceutical and chemical industry, it is a key intermediate for the synthesis of various drugs such as antibacterial and antihistamine drugs, and can also be used to construct bioactive molecules to assist biomedical research; in the surfactant field, it can be used to prepare cationic surfactants with emulsifying, bactericidal and other properties, as well as amphoteric surfactants with good biocompatibility and low irritation.

[0004] 2,4-Dinitrotoluene (2,4-DNT) can be successfully prepared into 2,4-HTDA by selective hydrogenation over an Ru-based catalyst. This process is a typical gas-liquid-solid multiphase catalytic reaction process. Developing a high-performance Ru-based catalyst is the key to developing the production process of 2,4-HTDA. Generally, the precursor of the Ru-based catalyst is prepared by the commonly used impregnation-precipitation method in industry, and then the precursor is placed in a fixed-bed reactor and calcined and reduced at high temperature to finally obtain a high-performance Ru-based catalyst. In the development stage of the small-scale technology for the selective hydrogenation of 2,4-DNT to 2,4-HTDA, 2,4-DNT can be converted into 2,4-HTDA through an unformed powdered Ru-based catalyst; however, when developing the pilot production technology or industrial technology of 2,4-HTDA, many problems will be faced in the scale-up preparation and engineering application of the Ru-based catalyst, mainly including: ① The powdered Ru-based catalyst has low strength and high wear rate in the reaction kettle, resulting in a large loss rate of the catalyst and increasing the production cost of 2,4-HTDA; ② The scale-up reduction process of the Ru-based catalyst must be carried out in a fixed-bed reactor. After filling a large amount of powdered catalyst precursor in the fixed bed, the void fraction in the bed is too low, and hydrogen cannot fully contact the precursor, resulting in the precursor not being fully reduced, and even causing gas path blockage in the bed, bringing potential production safety hazards. Therefore, by developing a catalyst forming method to improve the key indexes such as the strength, bulk density and catalytic performance of the Ru-based catalyst has become the only way and inevitable choice to realize the scale-up preparation of the Ru-based catalyst and the industrial production of 2,4-HTDA. Summary of the Invention

[0005] In view of this, the object of the present invention is to provide a method for forming a Ru-based catalyst for catalytic hydrogenation of 2,4-dinitrotoluene to prepare 1-methyl-2,4-cyclohexanediamine. The formed Ru-based catalyst prepared by the present invention has excellent mechanical strength, superior catalytic activity and stability, which is conducive to promoting the industrialization process of the technology for one-step hydrogenation of 2,4-DNT to 2,4-HTDA.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] The present invention provides a method for forming a Ru-based catalyst for catalytic hydrogenation of 2,4-dinitrotoluene to prepare 1-methyl-2,4-cyclohexanediamine, including: uniformly mixing a first catalyst precursor, a second catalyst precursor and a binder to obtain a mixed powder; then adding an adhesive, stirring until it becomes a paste, and then performing extrusion molding, cutting, drying, calcination, and hydrogen reduction to obtain the formed Ru-based catalyst;

[0008] The first catalyst precursor is one of Ru2(CO3)3 / support and Ru2(CO3)3-Rh2(CO3)3 / support;

[0009] The second catalyst precursor is RuO x / support, RuO x -RhO x / support.

[0010] As a preferred embodiment of the present invention, the first catalyst precursor is Ru2(CO3)3-Rh2(CO3)3 / support, and the mass ratio of Ru to Rh therein is 1:(0.1-10), and the second catalyst precursor is RuO x -RhO x / support, and the mass ratio of Ru to Rh therein is 1:(0.1-10).

[0011] Furthermore, the preparation method of the first catalyst precursor Ru2(CO3)3-Rh2(CO3)3 / support includes the following steps:

[0012] (1) First, dry the support at 60-120°C for 1-24 h, then grind it, pass it through a 200-mesh sieve, and then put it into a desiccator for later use;

[0013] (2) Add an aqueous solution of RuCl3 with a concentration of 0.1-2.0 mol / L and an aqueous solution of RhCl3 with a concentration of 0.1-2.0 mol / L to a container containing the support, and impregnate for 1-24 h under strong stirring to obtain solution A;

[0014] (3) Add an aqueous carbonate solution dropwise to solution A. After the addition is complete, age for 1 to 24 h;

[0015] (4) Filter the mixture obtained in step (3) and dry at 60 to 120 °C for 1 to 24 h;

[0016] (5) Grind the dried precursor and pass it through a 200-mesh sieve to obtain the first catalyst precursor Ru2(CO3)3-Rh2(CO3)3 / support.

[0017] Preferably, in step (1), the support is activated carbon (AC).

[0018] Preferably, in step (3), the concentration of the aqueous carbonate solution is 0.1 to 2 mol / L, and the carbonate is one of sodium carbonate, ammonium carbonate, and potassium carbonate.

[0019] Further, the preparation method of the second catalyst precursor RuO x -RhO x / support is as follows: Weigh the first catalyst precursor Ru2(CO3)3-Rh2(CO3)3 / support, place it in a muffle furnace, calcine at 200 to 700 °C for 1 to 8 h, and cool to room temperature to obtain the second catalyst precursor RuO x -RhO x / support.

[0020] As a preferred embodiment of the present invention, the binder is pseudoboehmite or a mixture of pseudoboehmite and aluminosol, and pseudoboehmite and aluminosol are mixed in a mass ratio of 1:(0 to 10).

[0021] As a preferred embodiment of the present invention, the first catalyst precursor accounts for 10 to 30% of the total mass of the mixed powder, the second catalyst precursor accounts for 50 to 70% of the total mass of the mixed powder, the binder accounts for 20 to 30% of the total mass of the mixed powder, and the particle size of the mixed powder is 100 to 300 mesh.

[0022] As a preferred embodiment of the present invention, the adhesive is a nitric acid aqueous solution with a concentration of 1 to 10 wt%, the mass of nitric acid in the nitric acid aqueous solution accounts for 30 to 50% of the sum of the mass of the mixed powder and nitric acid, and the sum of the mass of the binder and the adhesive accounts for 5 to 50% of the total mass of the mixed powder and the adhesive.

[0023] As a preferred embodiment of the present invention, the unformed catalyst after cutting is vacuum dried at 105 °C for 12 h, and then placed in a fixed-bed reactor with an inner diameter of 10 mm for calcination. It is heated under a purge of high-purity nitrogen, and the heating rate is 10 °C / min. After reaching the hydrogen reduction temperature, it is kept at a constant temperature. The hydrogen reduction temperature is 400 °C, and high-purity hydrogen is introduced to reduce the catalyst precursor. The hydrogen pressure is 0.5 MPa, and the reduction time is 4 h. The reduced catalyst is cooled to room temperature under the protection of high-purity nitrogen to obtain the formed Ru-based catalyst. The length of the formed Ru-based catalyst is 5-10 mm, and the strength is above 45 N / cm.

[0024] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0025] 1. The present invention not only uses the first catalyst precursor to replace the traditional extrusion aid, sesbania powder, but also because the main component of the first catalyst precursor is carbonate, carbon dioxide (CO2) will be generated during the subsequent high-temperature hydrogen reduction process. When CO2 is discharged, it will expand the pores of the catalyst. Therefore, it is beneficial to expose the active sites on the surface and interface of the carrier, and further improve the overall performance of the Ru-based catalyst while ensuring the strength of the catalyst.

[0026] 2. Both the first catalyst precursor and the second catalyst precursor used in the present invention contain metals Rh and Rh. The formed Ru-Rh alloy can improve the stability and reaction activity of the catalyst, and has excellent mechanical strength, high compressive strength and good wear resistance, which can meet the requirements of the industrial application scenario of hydrogenating 2,4-DNT to 2,4-HTDA.

[0027] 3. The strength of the formed Ru-based catalyst of the present invention reaches above 45 N / cm. Under the conditions of a reaction temperature of 180 °C and a hydrogen pressure of 6 MPa, it is used for the one-step hydrogenation of 2,4-DNT to produce 2,4-HTDA. The conversion rate of 2,4-DNT can reach 99.9%, and the selectivity of 2,4-HTDA is above 85%. After being reused 10 times, the catalytic activity is not significantly reduced. Therefore, it has good stability and meets the requirements of industrial applications. Description of the Drawings

[0028] Figure 1 It is the X-ray diffraction (XRD) pattern of the catalyst in Example 1 and the catalyst in Comparative Example 1;

[0029] Figure 2 It is the X-ray photoelectron spectroscopy (XPS) pattern of the catalyst in Example 1 and the catalyst in Comparative Example 1; among them, Figure 2 a is the total XPS spectrum of the catalyst in Comparative Example 1, Figure 2 b is the total XPS spectrum of the catalyst in Example 1, Figure 2 c is the fine spectrum of Ru metal of the catalyst in Comparative Example 1,Figure 2 d is the fine spectrum of Ru metal in the catalyst of Example 1;

[0030] Figure 3 are the high-resolution transmission electron microscopy (TEM) images of the catalysts after Example 1, Comparative Example 1, and 10 cycles of Example 1; among them, Figure 3 a is the TEM image of the catalyst in Comparative Example 1 at a scale of 100 nm, Figure 3 b is the TEM image of the catalyst in Comparative Example 1 at a scale of 20 nm, Figure 3 c is the TEM image of the catalyst in Example 1 at a scale of 100 nm, Figure 3 d is the TEM image of the catalyst in Example 1 at a scale of 20 nm, Figure 3 e is the TEM image of the catalyst in Example 1 after being used 10 times at a scale of 100 nm, Figure 3 f is the TEM image of the catalyst in Example 1 after being used 10 times at a scale of 20 nm;

[0031] Figure 4 are the comparison of the metal loadings of the catalysts after Example 1, Comparative Example 1, and 10 cycles of Example 1 (ICP-OES). Detailed implementation manners

[0032] The technical solutions in the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0033] In the present invention, unless otherwise specified, the raw materials involved are well-known commercially available products in the art.

[0034] A method for forming a Ru-based catalyst for catalytic hydrogenation of 2,4-dinitrotoluene to prepare 1-methyl-2,4-cyclohexanediamine provided by the present invention includes: uniformly mixing a first catalyst precursor, a second catalyst precursor, and a binder in a certain ratio to obtain a mixed powder; then adding a certain amount of adhesive, stirring until it becomes a gel state, and then performing extrusion molding, cutting, drying, calcination, and hydrogen reduction to obtain the formed Ru-based catalyst.

[0035] In the present invention, the first catalyst precursor is one of Ru2(CO3)3 / support, Ru2(CO3)3-Rh2(CO3)3 / support; the second catalyst precursor is RuO x / support, RuO x -RhO x / support.

[0036] In the present invention, the first catalyst precursor is preferably Ru2(CO3)3-Rh2(CO3)3 / support, where the mass ratio of Ru to Rh is 1:(0.1-10), and the second catalyst precursor is preferably RuO x -RhO x / support, where the mass ratio of Ru to Rh is 1:(0.1-10), and the support is preferably activated carbon (AC).

[0037] In the present invention, the binder is pseudoboehmite or a mixture of pseudoboehmite and aluminosol, and pseudoboehmite and aluminosol are mixed in a mass ratio of 1:(0-10).

[0038] In the present invention, the first catalyst precursor accounts for 10-30% of the total mass of the mixed powder, the second catalyst precursor accounts for 50-70% of the total mass of the mixed powder, and the binder accounts for 20-30% of the total mass of the mixed powder; the total mass of the first catalyst precursor and the second catalyst precursor preferably accounts for 60-90% of the total mass of the mixed powder, and more preferably 70-80%. The particle size of the mixed powder is preferably 100-300 mesh, more preferably 150-250 mesh, and further preferably 200 mesh.

[0039] In the present invention, the adhesive is an aqueous nitric acid solution with a concentration of 1-10 wt%, preferably 6-8%, and more preferably 3-5%. The aqueous nitric acid solution is prepared by adding water to commercially available concentrated nitric acid sol; the mass of nitric acid in the aqueous nitric acid solution accounts for 30-50% of the sum of the mass of the mixed powder and nitric acid, preferably 35-45%; the sum of the mass of the binder and the adhesive accounts for 5-50% of the total mass of the mixed powder and the adhesive.

[0040] In the present invention, the unformed catalyst after cutting is vacuum dried at 110°C for 1-24 h, and then placed in a fixed-bed reactor with an inner diameter of 10 mm for calcination. It is heated under a purge of high-purity nitrogen, and the heating rate is 2-20°C / min. After rising to the hydrogen reduction temperature, it is kept at a constant temperature. The hydrogen reduction temperature is 200-600°C. High-purity hydrogen is introduced to reduce the catalyst precursor, the hydrogen pressure is 0.01-1 MPa, and the reduction time is 1-8 h. The reduced catalyst is cooled to room temperature under the protection of high-purity nitrogen to obtain the formed Ru-based catalyst.

[0041] In the present invention, the first catalyst precursor acts as an extrusion aid during the extrusion molding process and becomes a catalyst after calcination and reduction, without introducing other components additionally. Therefore, it has no negative impact on the reaction performance of the formed Ru-based catalyst. At the same time, the first catalyst precursor releases carbon dioxide gas during the calcination and reduction process, which expands the pores of the catalyst, exposes more active sites, and improves the catalyst activity.

[0042] In the present invention, there are no special requirements for the extruder used for extrusion molding, and corresponding mechanical equipment well-known to those skilled in the art can be adopted. The particle size, bulk density and strength of the formed Ru-based catalyst can be regulated by controlling parameters such as the dosage and ratio of the first catalyst precursor and the second catalyst precursor, the type and dosage of the binder, the size of the mold, and the concentration and addition amount of the aqueous nitric acid solution during the extrusion molding process.

[0043] In the present invention, preferably, the extruded and formed product is a cylinder with a diameter of 2 - 6 mm and a length of 10 - 30 mm, and the strength of the formed Ru-based catalyst is controlled above 40 N / cm, preferably above 45 N / cm, and more preferably 45 - 50 N / cm, that is, the parameter settings for extrusion molding are only required to ensure the obtained formed catalyst has the above-mentioned size and strength.

[0044] In the present invention, the drying temperature is 90 - 120 °C, preferably 100 - 120 °C, and the time is 1 - 24 h, preferably 4 - 12 h. The processes of calcination and hydrogen reduction are mainly that the carbonate in the first catalyst precursor decomposes to release CO2, which expands the pores of the catalyst. At the same time, the bonding of dilute nitric acid with the carrier can make the thermal stability and strength of the catalyst better. In the present invention, the drying and calcination of the formed catalyst precursor are carried out in stages under different temperature conditions, and the mechanical strength of the formed Ru-based catalyst can be improved by adjusting the addition amount of pseudo-boehmite, the removal rate of moisture, etc.

[0045] The formed Ru-based catalyst prepared by the above technical solution is mainly used for catalyzing the hydrogenation of 2,4-DNT to prepare 2,4-HTDA.

[0046] In the present invention, the method for the formed Ru-based catalyst to catalyze the hydrogenation of 2,4-DNT to prepare 2,4-HTDA is specifically as follows: The formed Ru-based catalyst is loaded into a reaction kettle, and the solvent 2,4-HTDA, the reaction substrate 2,4-DNT and the deamination inhibitor are added. Then, nitrogen is introduced to test the airtightness of the reaction kettle and displace the air in the kettle. After that, the nitrogen in the kettle is displaced with hydrogen, and then 6 MPa of hydrogen is introduced and sealed. When the temperature rises to the set temperature, the rotation speed is adjusted to 1500 r / min, and the reaction starts to be timed. When the hydrogen pressure in the kettle no longer changes, it indicates that the hydrogenation reaction is over, and the temperature is lowered to take samples. The product composition is comprehensively analyzed by a gas chromatograph, a gas chromatography-mass spectrometry instrument, and a liquid chromatograph.

[0047] Specifically, a 100 mL reaction kettle is adopted, and the addition amount of the 2,4-HTDA solvent in the reaction kettle is preferably 30 - 60 mL, more preferably 40 mL; the reaction temperature is preferably 140 - 200 °C, more preferably 160 - 180 °C.

[0048] Example 1

[0049] 2.0 g of the first catalyst precursor Ru2(CO3)3-Rh2(CO3)3 / AC and 7.5 g of the second catalyst precursor RuO x -RhO x / AC and 2.0g of a binder are fully mixed, and then passed through a 200-mesh sieve to obtain a mixed powder; 7.5 mL of a 5wt% nitric acid solution is prepared as an adhesive; the mixed powder and the adhesive are mixed and molded in a beaker, and extruded and cut by an extruder; dried at 105°C for 12h, and then calcined in a fixed bed reactor with an inner diameter of 10mm, heated under high-purity nitrogen purge at a heating rate of 10°C / min, and kept at a constant temperature after reaching 400°C, and hydrogen with a pressure of 0.5MPa is introduced for reduction for 4h. The reduced catalyst is cooled to room temperature under the protection of high-purity nitrogen to obtain a cylindrical Ru-based catalyst with a diameter of 3mm and a length of 5-10mm.

[0050] In this embodiment, the mass ratio of Ru to Rh in the first catalyst precursor Ru2(CO3)3-Rh2(CO3)3 / AC is 4:1, and the mass ratio of Ru to Rh in the second catalyst precursor RuO x -RhO x The mass ratio of Ru to Rh in the / AC is 4:1, and the mass ratio of pseudo-boehmite to alumina sol in the binder is 1:1.

[0051] Example 2

[0052] 2.0 g of the first catalyst precursor Ru2(CO3)3 / AC and 7.5 g of the second catalyst precursor RuO x / AC and 2.0g of a binder are fully mixed, and then passed through a 200-mesh sieve to obtain a mixed powder; 7.5 mL of a 5wt% dilute nitric acid solution is prepared as an adhesive; the mixed powder and the adhesive are mixed and molded in a beaker, and extruded and cut by an extruder; the molded strip catalyst is dried at 105°C for 12h, and then placed in a fixed bed reactor with an inner diameter of 10mm for calcination, and heated under high-purity nitrogen purge at a heating rate of 10°C / min. After heating to 400°C, the temperature is maintained constant, and hydrogen with a pressure of 0.5MPa is introduced for reduction for 4h. The reduced catalyst is cooled to room temperature under the protection of high-purity nitrogen to obtain a cylindrical Ru-based catalyst with a diameter of 3mm and a length of 5-10mm.

[0053] In this embodiment, the mass ratio of pseudo-boehmite to aluminum sol in the binder is 1:2.

[0054] Example 3

[0055] 2.0 g of the first catalyst precursor Ru2(CO3)3-Rh2(CO3)3 / AC and 7.5 g of the second catalyst precursor RuO x -RhO x / AC and 2.0g pseudo-boehmite are fully mixed, and then passed through a 200-mesh sieve to obtain a mixed powder; 7.5 mL of 5wt% nitric acid solution is prepared as an adhesive; the mixed powder and the adhesive are mixed and molded in a beaker, and extruded and cut by an extruder; dried at 105°C for 12h, and then calcined in a fixed bed reactor with an inner diameter of 10mm, heated under high-purity nitrogen purge at a heating rate of 10°C / min, and kept at a constant temperature after reaching 400°C, and hydrogen with a pressure of 0.5MPa is introduced for reduction for 4h. The reduced catalyst is cooled to room temperature under the protection of high-purity nitrogen to obtain a cylindrical Ru-based catalyst with a diameter of 3mm and a length of 5-10mm.

[0056] In this embodiment, the mass ratio of Ru to Rh in the first catalyst precursor Ru2(CO3)3-Rh2(CO3)3 / AC is 4:1, and the mass ratio of Ru to Rh in the second catalyst precursor RuO x -RhO x The mass ratio of Ru to Rh in AC is 4:1.

[0057] Comparative Example 1

[0058] 2.0 g of the first catalyst precursor Ru2(CO3)3-Rh2(CO3)3 / AC and 7.5 g of the second catalyst precursor RuO x -RhO x / AC were fully mixed and then passed through a 200-mesh sieve to obtain a mixed powder; dried at 105°C for 12 hours, and then calcined and reduced at 400°C in a hydrogen atmosphere for 4 hours to obtain the unformed Ru-based catalyst of this comparative example.

[0059] In this comparative example, the mass ratio of Ru to Rh in the first catalyst precursor Ru2(CO3)3-Rh2(CO3)3 / AC is 4:1, and the mass ratio of Ru to Rh in the second catalyst precursor RuO x -RhO x The mass ratio of Ru to Rh in AC is 4:1.

[0060] Comparative Example 2

[0061] 2.0 g of the first catalyst precursor Ru2(CO3)3-Rh2(CO3)3 / AC and 7.5 g of the second catalyst precursor RuO x -RhO xMix 2.0 g of / AC and 2.0 g of aluminum sol thoroughly, then pass through a 200-mesh sieve to obtain a mixed powder; prepare 7.5 mL of 5wt% nitric acid solution as the adhesive; use a beaker to mix and form the above-mentioned mixed powder and the adhesive, and perform extrusion molding and cutting through an extrusion molding machine; place it in an oven at 105 °C for drying for 12 h, then place it in a fixed-bed reactor with an inner diameter of 10 mm for calcination, heat it up under a purge of high-purity nitrogen, with a heating rate of 10 °C / min, keep it at a constant temperature after rising to 400 °C, introduce hydrogen with a pressure of 0.5 MPa, reduce for 4 h, and cool the reduced catalyst to room temperature under the protection of high-purity nitrogen to obtain a cylindrical shaped Ru-based catalyst with a diameter of 3 mm and a length of 5 - 10 mm.

[0062] In this comparative example, the mass ratio of Ru to Rh in the first catalyst precursor Ru2(CO3)3 - Rh2(CO3)3 / AC is 4:1, and the mass ratio of Ru to Rh in the second catalyst precursor RuO x -RhO x / AC is 4:1.

[0063] Comparative Example 3

[0064] Mix 2.0 g of sesbania powder, 7.5 g of the second catalyst precursor RuO x -RhO x / AC and 2.0 g of binder thoroughly, then pass through a 200-mesh sieve to obtain a mixed powder; prepare 7.5 mL of 5wt% nitric acid solution as the adhesive; use a beaker to mix and form the above-mentioned mixed powder and the adhesive, and perform extrusion molding and cutting through an extrusion molding machine; place it in an oven at 105 °C for drying for 12 h, then place it in a fixed-bed reactor with an inner diameter of 10 mm for calcination, heat it up under a purge of high-purity nitrogen, with a heating rate of 10 °C / min, keep it at a constant temperature after rising to 400 °C, introduce hydrogen with a pressure of 0.5 MPa, reduce for 4 h, and cool the reduced catalyst to room temperature under the protection of high-purity nitrogen to obtain a cylindrical shaped Ru-based catalyst with a diameter of 3 mm and a length of 5 - 10 mm.

[0065] In this comparative example, the mass ratio of Ru to Rh in the first catalyst precursor Ru2(CO3)3 - Rh2(CO3)3 / AC is 4:1, and the mass ratio of Ru to Rh in the second catalyst precursor RuO x -RhO x / AC is 4:1, and the mass ratio of pseudoboehmite to aluminum sol in the binder is 1:1.

[0066] Comparative Example 4

[0067] Mix 2.0 g of PEG - 400, 7.5 g of the second catalyst precursor RuO x -RhO xMix the / AC and g binder thoroughly, then pass through a 200-mesh sieve to obtain the mixed powder; prepare 7.5 mL of a 5wt% nitric acid solution as the adhesive; use a beaker to mix and mold the above-mentioned mixed powder and the adhesive, and perform extrusion molding and cutting through an extrusion molding machine; place it in an oven at 105°C for drying for 12 h, then place it in a fixed-bed reactor with an inner diameter of 10 mm for calcination, heat it up under a purge of high-purity nitrogen, with a heating rate of 10°C / min, keep the temperature constant after rising to 400°C, introduce hydrogen with a pressure of 0.5 MPa, and reduce for 4 h. The reduced catalyst is cooled to room temperature under the protection of high-purity nitrogen to obtain a cylindrical-shaped Ru-based catalyst with a diameter of 3 mm and a length of 5 - 10 mm.

[0068] In this comparative example, the mass ratio of Ru to Rh in the first catalyst precursor Ru2(CO3)3-Rh2(CO3)3 / AC is 4:1, and the second catalyst precursor RuO x -RhO x / AC has a mass ratio of Ru to Rh of 4:1, and the mass ratio of pseudoboehmite to aluminosol in the binder is 1:1.

[0069] Comparative Example 5

[0070] Mix 2.0 g of magnesium stearate, 7.5 g of the second catalyst precursor RuO x -RhO x / AC and 2.0 g of the binder thoroughly, then pass through a 200-mesh sieve to obtain the mixed powder; prepare 7.5 mL of a 5wt% nitric acid solution as the adhesive; use a beaker to mix and mold the above-mentioned mixed powder and the adhesive, and perform extrusion molding and cutting through an extrusion molding machine; place it in an oven at 105°C for drying for 12 h, then place it in a fixed-bed reactor with an inner diameter of 10 mm for calcination, heat it up under a purge of high-purity nitrogen, with a heating rate of 10°C / min, keep the temperature constant after rising to 400°C, introduce hydrogen with a pressure of 0.5 MPa, and reduce for 4 h. The reduced catalyst is cooled to room temperature under the protection of high-purity nitrogen to obtain a cylindrical-shaped Ru-based catalyst with a diameter of 3 mm and a length of 5 - 10 mm.

[0071] In this comparative example, the mass ratio of Ru to Rh in the first catalyst precursor Ru2(CO3)3-Rh2(CO3)3 / AC is 4:1, and the second catalyst precursor RuO x -RhO x / AC has a mass ratio of Ru to Rh of 4:1, and the mass ratio of pseudoboehmite to aluminosol in the binder is 1:1.

[0072] Comparative Example 6

[0073] Mix 2.0 g of dry starch, 7.5 g of the second catalyst precursor RuO x-RhO x / AC and g binder are fully mixed, and then passed through a 200-mesh sieve to obtain a mixed powder; 7.5 mL of 5wt% nitric acid solution is prepared as an adhesive; the mixed powder and the adhesive are mixed and molded in a beaker, and extruded and cut by an extruder; dried at 105°C for 12 hours, and then calcined in a fixed bed reactor with an inner diameter of 10 mm, heated under high-purity nitrogen purge at a heating rate of 10°C / min, and kept at a constant temperature after reaching 400°C, and hydrogen with a pressure of 0.5MPa is introduced for reduction for 4 hours. The reduced catalyst is cooled to room temperature under the protection of high-purity nitrogen to obtain a cylindrical Ru-based catalyst with a diameter of 3 mm and a length of 5 to 10 mm.

[0074] In this comparative example, the mass ratio of Ru to Rh in the first catalyst precursor Ru2(CO3)3-Rh2(CO3)3 / AC is 4:1, and the mass ratio of Ru to Rh in the second catalyst precursor RuO x -RhO x The mass ratio of Ru to Rh in the / AC is 4:1, and the mass ratio of pseudo-boehmite to alumina sol in the binder is 1:1.

[0075] 1. Test on the influence of molding process on catalyst performance

[0076] The formed Ru-based catalyst in Example 1 and the unformed Ru-based catalyst in Comparative Example 1 were subjected to XRD and XPS tests, respectively. The test results are as follows: Figure 1 and 2 shown.

[0077] Figure 1It shows that the diffraction peaks of the (020), (120), (031), and (200) crystal planes of AIOOH (pseudo-boehmite) appear at 2θ = 14.4°, 28.2°, 38.5°, and 49.3° for the formed catalyst in Example 1, indicating that the carrier has AIOOH as the main crystal phase; metal characteristic peaks are observed at 2θ = 44.0° (Ru(101)) and 41.1° (Rh(111)), confirming the presence of the active components Ru and Rh; the carbonate additive added during the forming process can decompose during the subsequent reduction stage to produce a gas pore-expanding effect, but no carbonate residue peaks are detected by XRD (such as the carbonate characteristic peak near 2θ≈30° does not appear), indicating that it has completely decomposed during the reduction process. It should be noted that the diffraction peaks of the unformed catalyst in Comparative Example 1 are broadened and weak in intensity, showing poor crystallinity, while the diffraction peaks of the formed catalyst in Example 1 are significantly sharpened and enhanced in intensity at the same positions, indicating that the forming process significantly improves the crystallinity of the carrier AIOOH and metal particles. This change is due to the bonding effect of pseudo-boehmite promoting the ordered arrangement of particles, and the pore-expanding effect generated by the decomposition of the extrusion aid during reduction optimizing the structure, without introducing new phases (no impurity peaks) or causing metal sintering (no peak position shift). The improvement of crystallinity can enhance the mechanical strength and stability of the catalyst.

[0078] Figure 2 Reveals a significant effect of the forming process on the surface electronic properties of the catalyst, Figure 2 In c, the Ru 3p 3 / 2 peak (binding energy 280 - 290 eV) of the unformed catalyst in Comparative Example 1 shows a broadened feature, indicating a high dispersion of Ru species but possible oxidation states (Ru δ+ ); while Figure 2 In d, the Ru 3p 3 / 2 peak intensity of the sample after forming in Example 1 (adding pseudo-boehmite and active metal carbonate extrusion aid) is significantly enhanced and the peak shape is more symmetric, and the binding energy does not shift, indicating that the metal valence state has not changed but the surface enrichment degree has increased. From Figure 2 b, it can be seen that significant changes occur in the O1s spectrum of the formed catalyst in Example 1: an obvious characteristic peak of lattice oxygen (O 2- ) is observed to be enhanced at a binding energy of 531.5 eV, which is directly attributed to the introduction of pseudo-boehmite (AlOOH), which provides abundant surface hydroxyl groups (-OH) and structural oxygen sites. Compared with Figure 2 the unformed sample in Comparative Example 1 in c, the Ru 3p 3 / 2The intensity of the peak (280 - 290 eV) increased without a shift in the binding energy, indicating that the addition of pseudo - boehmite enhanced the dispersion of Ru species without changing their valence states. No impurities were introduced during the shaping process (no new XPS peaks), and the C1s peak (284.8 eV) was stably present, confirming the structural integrity of the support AC.

[0079] In summary, the shaping technology synergistically improved the catalyst performance through physical pore expansion and chemical modulation, offsetting the influence of pseudo - boehmite in the shaped catalyst that masked some active sites, enabling the catalyst to have appropriate strength while maintaining its catalytic performance without reduction.

[0080] II. Catalytic performance test

[0081] Test method: 0.04 g of the catalyst, 40 mL of the solvent 2,4 - HTDA, 0.01 g of lithium hydroxide, and 0.01 g of sodium borohydride were loaded into a 100 mL high - pressure reactor. The air in the autoclave was displaced with N2, and then the N2 in the autoclave was replaced with H2. The initial pressure of H2 was 6 MPa. During the heating process, the mixture was stirred at a speed of 50 r / min. After heating to the reaction temperature of 180 °C, the speed was adjusted to 1500 r / min. After the reaction for 4 h, the products were analyzed and detected.

[0082] Analysis method for product composition: The product distribution was quantitatively analyzed by Agilent 8860 gas chromatography and Tianmei LC2030 high - performance liquid chromatography, and the reaction products were qualitatively analyzed by Agilent 8860 GC / 5077 MSD gas chromatography - mass spectrometry.

[0083] The gas chromatography analysis conditions were as follows: The vaporization chamber temperature was 280 °C; the detector temperature was 280 °C; programmed temperature control was used, with the column temperature at 60 °C, staying for 3 min in the initial state, a heating rate of 10 °C / min, an end temperature of 200 °C, and staying for 10 min at the end temperature; the carrier gas was high - purity N2, the carrier gas flow rate was 30 mL / min, the split ratio was 1:45; the injection volume was 1 μL;

[0084] The gas chromatography - mass spectrometry analysis conditions were as follows: The gas chromatography column was an HP - 5MS UI capillary column (30 m×0.25 mm×0.25 μm) equipped with an FID detector; the interface temperature was set at 250 °C, the ion source temperature was 200 °C, the mass spectrometry detection mode was Full Scan, and the mass range was 35 - 400; the vaporization chamber temperature was 310 °C, the column head pressure was 22.97 psi, the detector temperature was 320 °C, and the column oven was heated according to the set program: the initial temperature was 50 °C, staying for 3 min at this initial temperature, and then heating at a rate of 10 °C / min to 200 °C, staying for 10 min at this temperature.

[0085] The analytical conditions of the liquid chromatography are as follows: ultraviolet detector (detection wavelength 280 nm), TM.X-C18 chromatographic column (4 μm, 4.6×250 mm), column temperature 35 °C, mobile phase methanol and water (3:2), injection volume 10 μL, flow rate 1 mL.

[0086] According to the above test method, the catalytic performance of the Ru-based catalysts prepared in Examples 1-3 and Comparative Examples 1-6 was detected respectively, and the test results are shown in Table 1.

[0087] Table 1 Catalytic performance of the Ru-based catalysts in Examples 1-3 and Comparative Examples 1-6

[0088]

[0089] III. Stability test

[0090] The stability test of the shaped Ru-based catalyst of Example 1 was carried out in a reactor, and the experimental results are shown in Table 2 and Figure 3 and Figure 4 As shown, under the conditions of a reaction temperature of 180 °C and a hydrogen pressure of 6 MPa, 2,4-DNT was catalytically hydrogenated to 2,4-HTDA.

[0091] Table 2 Catalytic performance results of the Ru-based catalyst of Example 3 used 10 times

[0092]

[0093] Table 2 shows that after the shaped Ru-based catalyst of Example 1 was used 10 times, the conversion rate of 2,4-DNT was still as high as 99.9%, and the selectivity of 2,4-HTDA was 88.5%. Other by-products include 1-methyl-2-aminocyclohexane, 1-methyl-4-aminocyclohexane, and methylcyclohexane, indicating that the shaped Ru-based catalyst in Example 1 has excellent stability and good industrial application prospects.

[0094] Figure 3 For the TEM characterization results, through Figure 3 a- Figure 3 d, it can be seen that the shaping process using pseudo-boehmite binding and mechanical pressing can effectively maintain the initial characteristics of the catalyst. The metal particle size is stable at about 1-3 nm, and it has no adverse effect on the catalytic efficiency. The conversion rate of 99.9% and the selectivity of 91.8% were achieved in the first reaction; secondly, through Figure 3 e and Figure 3As can be seen from f, the catalyst after forming in Example 1 exhibits excellent cyclic stability. After 10 reactions, only slight particle coarsening of 2 - 4 nm occurs, the conversion rate still remains at 99.9%, and the selectivity only drops to 88.5%. This limited performance decay is mainly due to the controllable particle coarsening process rather than the large-scale loss of active sites. These results indicate that while ensuring the catalytic efficiency, this forming process significantly improves the long-term stability of the catalyst.

[0095] Figure 4 The ICP - OES comparative analysis results of the unformed catalyst in Comparative Example 1 and the formed catalyst in Example 1 are shown. By comparison, it is found that the forming process in Example 1 only slightly reduces the Ru metal loading from 4.00 / 3.20 wt% to 3.97 / 3.17 wt%, indicating that the forming process has little impact on the loading of active components. More importantly, after 10 cycles in Example 1, the Ru / Rh metal content stabilizes from 3.20 / 0.80 wt% to 3.09 / 0.74 wt%, and the loss rate is controlled within 5%, fully meeting the industrial standard. It is confirmed that this forming process not only perfectly maintains the initial metal loading but also significantly improves the cyclic stability by optimizing the catalyst structure, making it have both excellent initial activity and long-term use performance.

[0096] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the technical solutions and concepts of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for forming an Ru-based catalyst for catalytic hydrogenation of 2,4-dinitrotoluene to prepare 1-methyl-2,4-cyclohexanediamine, characterized in that: The first catalyst precursor, the second catalyst precursor, and the binder are uniformly mixed in a certain ratio to obtain a mixed powder; then a certain amount of adhesive is added, and after stirring until it becomes gelatinous, it is extruded into strips, cut into segments, dried, calcined, and reduced with hydrogen to obtain the shaped Ru-based catalyst; The second catalyst precursor is RuO x -RhO x / support; The binder is pseudo-boehmite or a mixture of pseudo-boehmite and aluminum sol; The adhesive is an aqueous nitric acid solution with a concentration of 1-10 wt%; The preparation method of the first catalyst precursor is as follows: (1) First, dry the carrier at 60-120 °C for 1-24 h, then grind it, pass it through a 200-mesh sieve, and then place it in a desiccator for later use; (2) Add an aqueous RuCl3 solution with a concentration of 0.1-2.0 mol / L and an aqueous RhCl3 solution with a concentration of 0.1-2.0 mol / L to a container containing the carrier, and impregnate for 1-24 h under strong stirring to obtain solution A; (3) Drop the aqueous carbonate solution into solution A, and after dropping, age for 1-24 h; (4) Filter the mixed solution obtained in step (3), and dry it at 60-120 °C for 1-24 h; (5) Grind the dried precursor and pass it through a 200-mesh sieve to obtain the first catalyst precursor; The concentration of the aqueous carbonate solution is 0.1-2 mol / L, and the carbonate is one of sodium carbonate, ammonium carbonate, and potassium carbonate.

2. The shaping method of the Ru-based catalyst for catalytic hydrogenation of 2,4-dinitrotoluene to prepare 1-methyl-2,4-cyclohexanediamine according to claim 1, characterized in that: The mass ratio of Ru to Rh in the first catalyst precursor is 1:(0.1-10), and the mass ratio of Ru to Rh in the second catalyst precursor is 1:(0.1-10).

3. The forming method of the Ru-based catalyst for catalytic hydrogenation of 2,4-dinitrotoluene to prepare 1-methyl-2,4-cyclohexanediamine according to claim 1, characterized in that: In step (1), the carrier is activated carbon.

4. A method for forming an Ru-based catalyst for catalytic hydrogenation of 2,4-dinitrotoluene to prepare 1-methyl-2,4-cyclohexanediamine according to claim 1, characterized in that, The preparation method of the second catalyst precursor is: weigh the first catalyst precursor, place it in a muffle furnace, calcine it at 200-700 °C for 1-8 h, and cool it to room temperature to obtain the second catalyst precursor.

5. A method for forming an Ru-based catalyst for catalytic hydrogenation of 2,4-dinitrotoluene to prepare 1-methyl-2,4-cyclohexanediamine according to claim 1, characterized in that: Pseudo-boehmite and aluminum sol are mixed in a mass ratio of 1:(0-10).

6. A method for shaping an Ru-based catalyst for catalytic hydrogenation of 2,4-dinitrotoluene to prepare 1-methyl-2,4-cyclohexanediamine according to claim 1, characterized in that: The first catalyst precursor accounts for 10-30% of the total mass of the mixed powder, the second catalyst precursor accounts for 50-70% of the total mass of the mixed powder, the binder accounts for 20-30% of the total mass of the mixed powder, and the particle size of the mixed powder is 100-300 mesh.

7. A method for forming an Ru-based catalyst for catalytic hydrogenation of 2,4-dinitrotoluene to prepare 1-methyl-2,4-cyclohexanediamine according to claim 1, characterized in that: The mass of nitric acid in the aqueous nitric acid solution accounts for 30-50% of the sum of the mass of the mixed powder and nitric acid, and the sum of the mass of the binder and the adhesive accounts for 5-50% of the total mass of the mixed powder and the adhesive.

8. A method for forming an Ru-based catalyst for catalytic hydrogenation of 2,4-dinitrotoluene to prepare 1-methyl-2,4-cyclohexanediamine according to claim 1, characterized in that: The unshaped catalyst after cutting is vacuum dried at 105 °C for 12 h, then placed in a fixed-bed reactor with an inner diameter of 10 mm for calcination, heated under a high-purity nitrogen purge, the heating rate is 10 °C / min, and after rising to the hydrogen reduction temperature, it is kept at a constant temperature. The hydrogen reduction temperature is 400 °C, high-purity hydrogen is introduced to reduce the catalyst precursor, the hydrogen pressure is 0.5 MPa, the reduction time is 4 h, and the reduced catalyst is cooled to room temperature under the protection of high-purity nitrogen to obtain the shaped Ru-based catalyst. The length of the shaped Ru-based catalyst is 5-10 mm, and the strength is not less than 45 N / cm.

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