Forming method of Ru-based catalyst for catalyzing hydrogenation of 2, 4-dinitrotoluene to prepare 1-methyl-2, 4-cyclohexanediamine

Abstract

The invention discloses a forming method of a Ru-based catalyst for catalyzing hydrogenation of 2, 4-dinitrotoluene to prepare 1-methyl-2, 4-cyclohexanediamine, and the method comprises the following steps: uniformly mixing a first catalyst precursor, a second catalyst precursor and a binder to obtain mixed powder; then adding an adhesive, stirring to be colloidal, and performing extrusion molding, cutting, drying, roasting and hydrogen reduction to obtain a molded Ru-based catalyst; the first catalyst precursor is one of a Ru2 (CO3) 3 / carrier and Ru2 (CO3) 3-Rh2 (CO3) 3 / carrier; the second catalyst precursor is one of a RuOx / carrier and a RuOx-RhOx / carrier. The first catalyst precursor is adopted to replace a traditional extrusion aid sesbania powder, the first catalyst precursor and the second catalyst precursor both have metals Rh and Rh, the formed Ru-Rh alloy can improve the stability and reaction activity of the catalyst, has excellent mechanical strength, high compressive strength and good wear resistance, and can meet the requirements of hydrogenation of 2, 4-DNT to prepare 2, 4-DNT. And the requirements of industrial application scenes of 2, 4-HTDA are met.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and particularly relates to a method for forming a 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, tabletting forming, spray forming, rotary forming, etc.

[0003] 1-Methyl-2,4-cyclohexanediamine (2,4-HTDA) is an important organic compound, mainly used for producing 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 synthesizing polyamide resins; in the pharmaceutical and chemical industry, it is a key intermediate for synthesizing 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 and 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 with a 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 the 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 test technology for 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 in the large-scale preparation and engineering application of the Ru-based catalyst will be faced, mainly including: ① The strength of the powdered Ru-based catalyst is low, and the wear rate in the reaction kettle is high, resulting in a large loss rate of the catalyst and increasing the production cost of 2,4-HTDA; ② The large-scale 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 for realizing the large-scale 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 one-step hydrogenation of 2,4-DNT to 2,4-HTDA technology.

[0006] To achieve the above object, the present invention adopts the following technical solutions: 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 gel state, and then performing extrusion molding, cutting, drying, calcination, and hydrogen reduction to obtain the formed Ru-based catalyst; The first catalyst precursor is Ru 2 (CO 3 ) 3 / support, Ru 2 (CO 3 ) 3 -Rh 2 (CO 3 ) 3 / support; The second catalyst precursor is RuO x / support, RuO x -RhO x / support.

[0007] As a preferred embodiment of the present invention, the first catalyst precursor is Ru 2 (CO 3 ) 3 -Rh 2 (CO 3 ) 3 / support, wherein the mass ratio of Ru to Rh is 1:(0.1-10), and the second catalyst precursor is RuO x -RhO x / support, wherein the mass ratio of Ru to Rh is 1:(0.1-10).

[0008] Furthermore, the preparation method of the first catalyst precursor Ru 2 (CO 3 ) 3 -Rh 2 (CO 3 ) 3 / support includes the following steps: (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 place it in a desiccator for later use; (2) Add an aqueous solution of RuCl with a concentration of 0.1 - 2.0 mol / L and an aqueous solution of RhCl 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; 3 aqueous solution, an aqueous solution of RhCl with a concentration of 0.1 - 2.0 mol / L 3 Add to the container with the support, and impregnate for 1 - 24 h under strong stirring to obtain Solution A; (3) Drop the aqueous carbonate solution into Solution A. After the dropping is completed, 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 Ru 2 (CO 3 ) 3 -Rh 2 (CO 3 ) 3 / support.

[0009] Preferably, in step (1), the support is activated carbon (AC).

[0010] Preferably, in step (3), 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.

[0011] Further, the preparation method of the second catalyst precursor RuO x -RhO x / support is: Weigh the first catalyst precursor Ru 2 (CO 3 ) 3 -Rh 2 (CO 3 ) 3 / support, place it in a muffle furnace, calcine at 200 - 700 °C for 1 - 8 h, and cool to room temperature to obtain the second catalyst precursor RuO x -RhO x / support.

[0012] 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 - 10).

[0013] As a preferred embodiment of 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 particle size of the mixed powder is 100-300 mesh.

[0014] As a preferred embodiment of the present invention, the adhesive is an aqueous nitric acid solution with a concentration of 1-10 wt%. 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. 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.

[0015] 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 high-purity nitrogen purge, 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. 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.

[0016] Compared with the prior art, the beneficial technical effects of the present invention are as follows: 1. The present invention not only uses the first catalyst precursor to replace the traditional extrusion aid, sawdust. Moreover, since the main component of the first catalyst precursor is carbonate, carbon dioxide (CO 2 )will be decomposed during the subsequent high-temperature hydrogen reduction process. When CO 2 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 then improve the overall performance of the Ru-based catalyst while ensuring the strength of the catalyst.

[0017] 2. Both the first catalyst precursor and the second catalyst precursor used in the present invention have metals Rh, 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.

[0018] 3. The strength of the formed Ru-based catalyst of the present invention reaches more than 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 more than 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

[0019] Figure 1 It is the X-ray diffraction (XRD) pattern of the catalyst in Example 1 and the catalyst in Comparative Example 1; Figure 2 It is the X-ray photoelectron spectroscopy (XPS) pattern of the catalyst in Example 1 and the catalyst in Comparative Example 1; wherein, Figure 2 a is the total XPS pattern of the catalyst in Comparative Example 1, Figure 2 b is the total XPS pattern 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 of the catalyst in Example 1; Figure 3 It is the high-resolution transmission electron microscopy (TEM) images of the catalysts in Example 1, Comparative Example 1, and Example 1 after being recycled 10 times; wherein, 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 reused 10 times at a scale of 100 nm, Figure 3 f is the TEM image of the catalyst in Example 1 after being reused 10 times at a scale of 20 nm; Figure 4 It is the comparison of the metal loadings of the catalysts in Example 1, Comparative Example 1, and Example 1 after being recycled 10 times (ICP-OES). Detailed Embodiments

[0020] 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.

[0021] In the present invention, unless otherwise specified, the raw materials involved are commercially available products well-known in the art.

[0022] 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.

[0023] In the present invention, the first catalyst precursor is Ru 2 (CO 3 ) 3 / support, Ru 2 (CO 3 ) 3 -Rh 2 (CO 3 ) 3 / support; the second catalyst precursor is one of RuO x / support, RuO x -RhO x / support.

[0024] In the present invention, the first catalyst precursor is preferably Ru 2 (CO 3 ) 3 -Rh 2 (CO 3 ) 3 / support, where the mass ratio of Ru to Rh is 1:(0.1 - 10), 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).

[0025] In the present invention, the binder is pseudo-boehmite or a mixture of pseudo-boehmite and aluminum sol, and pseudo-boehmite and aluminum sol are mixed in a mass ratio of 1:(0 - 10).

[0026] 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.

[0027] In the present invention, the adhesive is an aqueous nitric acid solution with a concentration of 1 to 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 masses of the mixed powder and nitric acid, preferably 35 - 45%; the sum of the masses of the binder and the adhesive accounts for 5 - 50% of the total mass of the mixed powder and the adhesive.

[0028] In the present invention, the unformed catalyst after cutting is vacuum dried at 110 °C for 1 to 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.

[0029] In the present invention, the first catalyst precursor serves 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, expanding the pores of the catalyst and exposing more active sites, thereby improving the catalyst activity.

[0030] 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 used. The particle size, bulk density, and strength of the formed Ru-based catalyst can be regulated by controlling parameters such as the amounts and ratios of the first catalyst precursor and the second catalyst precursor, the type and amount 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.

[0031] 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. 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 such that the formed catalyst of the above size and strength can be obtained.

[0032] 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 the decomposition of carbonate in the first catalyst precursor to release CO 2, the pores of the catalyst are expanded, and the bonding of the dilute nitric acid and the carrier can make the catalyst thermally stable and strong. The present invention performs drying and calcining of the formed catalyst precursor in stages under different temperature conditions, and can improve the mechanical strength of the formed Ru-based catalyst by adjusting the addition amount of pseudo-boehmite, the removal speed of water, etc.

[0033] The shaped Ru-based catalyst prepared by the above technical scheme is mainly used to catalyze the hydrogenation of 2,4-DNT to prepare 2,4-HTDA.

[0034] In the present invention, the method for preparing 2,4-HTDA by hydrogenating 2,4-DNT with the shaped Ru-based catalyst is specifically as follows: the shaped Ru-based catalyst is loaded into a reactor, and a solvent 2,4-HTDA, a reaction substrate 2,4-DNT and a deamination inhibitor are added, and then nitrogen is introduced to test the air tightness of the reactor and replace the air in the reactor, and then the nitrogen in the reactor is replaced with hydrogen, and then 6MPa hydrogen is introduced and sealed, and the temperature is raised to the set temperature, the speed is adjusted to 1500r / min, and the reaction timing is started. When the hydrogen pressure in the reactor no longer changes, indicating that the hydrogenation reaction is completed, the temperature is lowered and sampling is started, and the product composition is comprehensively analyzed using a gas chromatograph, a gas chromatograph-gas spectrometer, and a liquid chromatograph.

[0035] Specifically, a 100 mL reactor is used, and the amount of 2,4-HTDA solvent added to the reactor is preferably 30 to 60 mL, more preferably 40 mL; the reaction temperature is preferably 140 to 200 °C, more preferably 160 to 180 °C.

[0036] Example 1 2.0 g of the first catalyst precursor Ru 2 (CO 3 ) 3 -Rh 2 (CO 3 ) 3 / AC, 7.5g 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.

[0037] In this embodiment, the first catalyst precursor Ru 2 (CO 3 ) 3 -Rh 2 (CO 3 ) 3 / AC has a mass ratio of Ru to Rh of 4:1. The second catalyst precursor RuO x -RhO x / AC has a mass ratio of Ru to Rh of 4:1. The mass ratio of pseudoboehmite to aluminosol in the binder is 1:1.

[0038] Example 2 Mix 2.0 g of the first catalyst precursor Ru 2 (CO 3 ) 3 / AC, 7.5 g of the second catalyst precursor RuO x / AC, and 2.0 g of the binder thoroughly. Then, pass through a 200-mesh sieve to obtain a mixed powder. Prepare 7.5 mL of a 5 wt% dilute 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 the molded strip catalyst 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 roasting. Heat it up under a high-purity nitrogen purge at a heating rate of 10 °C / min. After reaching 400 °C, keep it at a constant temperature, introduce hydrogen with a pressure of 0.5 MPa, and reduce it for 4 h. After reduction, the catalyst is cooled to room temperature under the protection of high-purity nitrogen to obtain a cylindrical molded Ru-based catalyst with a diameter of 3 mm and a length of 5 - 10 mm.

[0039] In this embodiment, the mass ratio of pseudoboehmite to aluminosol in the binder is 1:2.

[0040] Example 3 Mix 2.0 g of the first catalyst precursor Ru 2 (CO 3 ) 3 -Rh 2 (CO 3 ) 3 / AC, 7.5 g of the second catalyst precursor RuO x -RhO xMix 2.0 g of Ru(CO)₂(acac)₂ with 2.0 g of pseudoboehmite thoroughly, then pass through a 200-mesh sieve to obtain a mixed powder. Prepare 7.5 mL of a 5 wt% nitric acid solution as an adhesive. Use a beaker to mix the above-mentioned mixed powder and the adhesive for molding, and then 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 at a heating rate of 10 °C / min. After heating to 400 °C, keep it at a constant temperature, introduce hydrogen with a pressure of 0.5 MPa, and reduce it for 4 h. 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.

[0041] In this example, the first catalyst precursor Ru 2 (CO 3 ) 3 -Rh 2 (CO 3 ) 3 / AC has a mass ratio of Ru to Rh of 4:1, and the second catalyst precursor RuO x -RhO x / AC has a mass ratio of Ru to Rh of 4:1.

[0042] Comparative Example 1 Mix 2.0 g of the first catalyst precursor Ru 2 (CO 3 ) 3 -Rh 2 (CO 3 ) 3 / AC and 7.5 g of the second catalyst precursor RuO x -RhO x / AC thoroughly, then pass through a 200-mesh sieve to obtain a mixed powder. Place it in an oven at 105 °C for drying for 12 h, and then calcine and reduce it at 400 °C in a hydrogen atmosphere for 4 h to obtain the unshaped Ru-based catalyst of this comparative example.

[0043] In this comparative example, the first catalyst precursor Ru 2 (CO 3 ) 3 -Rh 2 (CO 3 ) 3 / AC has a mass ratio of Ru to Rh of 4:1, and the second catalyst precursor RuO x -RhO x / AC has a mass ratio of Ru to Rh of 4:1.

[0044] Comparative Example 2 Mix 2.0 g of the first catalyst precursor Ru 2(CO 3 ) 3 -Rh 2 (CO 3 ) 3 / AC, 7.5 g of the second catalyst precursor RuO x -RhO x / AC and 2.0 g of aluminum sol are fully mixed, then passed through a 200-mesh sieve to obtain a mixed powder; 7.5 mL of a 5 wt% nitric acid solution is prepared as the adhesive; the above-mentioned mixed powder and the adhesive are mixed and formed using a beaker, and then extruded and cut through an extrusion molding machine; it is 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, with a heating rate of 10 °C / min, kept at a constant temperature after reaching 400 °C, hydrogen with a pressure of 0.5 MPa is introduced, and reduced 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.

[0045] In this comparative example, the mass ratio of Ru to Rh in the first catalyst precursor Ru 2 (CO 3 ) 3 -Rh 2 (CO 3 ) 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.

[0046] Comparative Example 3 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 are fully mixed, then passed through a 200-mesh sieve to obtain a mixed powder; 7.5 mL of a 5 wt% nitric acid solution is prepared as the adhesive; the above-mentioned mixed powder and the adhesive are mixed and formed using a beaker, and then extruded and cut through an extrusion molding machine; it is 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, with a heating rate of 10 °C / min, kept at a constant temperature after reaching 400 °C, hydrogen with a pressure of 0.5 MPa is introduced, and reduced 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.

[0047] In this comparative example, the first catalyst precursor Ru 2 (CO 3 ) 3 -Rh2 (CO 3 ) 3 The mass ratio of Ru to Rh in Ru(CO) / AC is 4:1, and the second catalyst precursor RuO x -RhO x The mass ratio of Ru to Rh in RuO-RhO / AC is 4:1, and the mass ratio of pseudoboehmite to aluminosol in the binder is 1:1.

[0048] Comparative Example 4 Mix 2.0 g of PEG-400, 7.5 g of the second catalyst precursor RuO x -RhO x / AC and the binder thoroughly, then pass through a 200-mesh sieve to obtain a mixed powder; prepare 7.5 mL of a 5 wt% nitric acid solution as the adhesive; use a beaker to mix and mold the above mixed powder and the adhesive, and perform extrusion molding and cutting through an extrusion molding machine; dry at 105 °C for 12 h, then place in a fixed-bed reactor with an inner diameter of 10 mm for calcination, heat up under a high-purity nitrogen purge, 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, 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.

[0049] In this comparative example, the first catalyst precursor Ru 2 (CO 3 ) 3 -Rh 2 (CO 3 ) 3 The mass ratio of Ru to Rh in Ru(CO)-Rh(CO) / AC is 4:1, and the second catalyst precursor RuO x -RhO x The mass ratio of Ru to Rh in RuO-RhO / AC is 4:1, and the mass ratio of pseudoboehmite to aluminosol in the binder is 1:1.

[0050] Comparative Example 5 Mix 2.0 g of magnesium stearate, 7.5 g of the second catalyst precursor RuO x -RhO xMix 2.0 g of / AC and the binder thoroughly, then pass through a 200-mesh sieve to obtain the mixed powder; prepare 7.5 mL of a 5 wt% 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; dry at 105 °C for 12 h, then place in a fixed-bed reactor with an inner diameter of 10 mm for calcination, heat up under a high-purity nitrogen purge, with a heating rate of 10 °C / min, maintain 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.

[0051] In this comparative example, the first catalyst precursor Ru 2 (CO 3 ) 3 -Rh 2 (CO 3 ) 3 / AC has a mass ratio of Ru to Rh of 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.

[0052] Comparative Example 6 Mix 2.0 g of dry starch, 7.5 g of the second catalyst precursor RuO x -RhO x / AC and the binder thoroughly, then pass through a 200-mesh sieve to obtain the mixed powder; prepare 7.5 mL of a 5 wt% 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; dry at 105 °C for 12 h, then place in a fixed-bed reactor with an inner diameter of 10 mm for calcination, heat up under a high-purity nitrogen purge, with a heating rate of 10 °C / min, maintain 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.

[0053] In this comparative example, the first catalyst precursor Ru 2 (CO 3 ) 3 -Rh 2 (CO 3 ) 3 / AC has a mass ratio of Ru to Rh of 4:1, and the second catalyst precursor RuO x -RhO xThe mass ratio of Ru to Rh in / AC is 4:1, and the mass ratio of pseudoboehmite to aluminosol in the binder is 1:1.

[0054] I. Influence test of shaping process on catalyst performance The shaped Ru-based catalyst in Example 1 and the unshaped Ru-based catalyst in Comparative Example 1 were respectively subjected to XRD and XPS tests, and the test results are as Figure 1 and 2 shown.

[0055] Figure 1 The results show that for the shaped catalyst in Example 1, diffraction peaks of the (020), (120), (031), and (200) crystal planes of AIOOH (pseudoboehmite) appear at 2θ = 14.4°, 28.2°, 38.5°, and 49.3°, indicating that the carrier is mainly composed of AIOOH as the 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 shaping 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 unshaped catalyst in Comparative Example 1 are broadened and weak in intensity, showing poor crystallinity, while the diffraction peaks of the shaped catalyst in Example 1 are significantly sharpened and enhanced in intensity at the same positions, indicating that the shaping process significantly improves the crystallinity of the carrier AIOOH and metal particles. This change is due to the binding effect of pseudoboehmite promoting the orderly 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.

[0056] Figure 2 It reveals the significant influence of the shaping 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 unshaped catalyst in Comparative Example 1 shows a broadened feature, indicating a high dispersion of Ru species but possible existence of an oxidized state (Ru δ+ ); while Figure 2 in d, the Ru 3p 3 / 2 peak intensity of the sample after shaping in Example 1 (adding pseudoboehmite 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. As can be seen from Figure 2 b, significant changes occur in the O1s spectrum of the shaped catalyst in Example 1: obvious lattice oxygen (O2- )The characteristic peaks are enhanced, which is directly attributed to the introduction of boehmite (AlOOH), which provides abundant surface hydroxyl groups (-OH) and structural oxygen sites. Compared with Figure 2 the unformed sample of Comparative Example 1 in c, the Ru 3p 3 / 2 peak (280 - 290 eV) intensity of the formed sample in Example 1 is increased but the binding energy does not shift, indicating that the addition of boehmite enhances the dispersion of Ru species without changing their valence states. No impurities are introduced during the forming process (no new XPS peaks), and the C1s peak (284.8 eV) stably exists, confirming the structural integrity of the support AC.

[0057] In summary, the forming technology synergistically improves the catalyst performance through physical pore expansion and chemical modulation, offsetting the influence of boehmite in the formed catalyst that masks some active sites, so that while obtaining the appropriate strength of the catalyst, the catalytic performance is not reduced.

[0058] II. Catalytic performance test 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 are loaded into a 100 mL high-pressure reactor together. Use N 2 to expel the air in the autoclave, and then use H 2 to displace the N in the autoclave 2 , and the initial pressure of H 2 is 6 MPa. During the heating process, stir at a speed of 50 r / min. After heating to the reaction temperature of 180 °C, adjust the speed to 1500 r / min. After reacting for 4 h, analyze and detect the products.

[0059] Analysis method for product composition: Use Agilent 8860 gas chromatography and Tianmei LC2030 high-performance liquid chromatography to quantitatively analyze the product distribution, and use Agilent 8860 GC / 5077 MSD gas chromatography-mass spectrometry to qualitatively analyze the reaction products.

[0060] The gas chromatography analysis conditions are as follows: The vaporization chamber temperature is 280 °C; the detector temperature is 280 °C; Programmed temperature rise is used, the column temperature is 60 °C, stay in the initial state for 3 min, the heating rate is 10 °C / min, the end temperature is 200 °C, and the end time is maintained for 10 min; The carrier gas uses high-purity N 2 , the carrier gas flow rate is 30 mL / min, the split ratio is 1:45; the injection volume is 1 μL; The analysis conditions of the gas chromatography-mass spectrometry are as follows: The gas chromatography column uses an HP-5MS UI capillary column (30m×0.25mm×0.25μm) and is equipped with an FID detector; the temperature of the interface is set at 250 °C, the temperature of the ion source is 200 °C, the mass spectrometry detection mode is Full Scan, and the mass range is 35 - 400; the temperature of the vaporization chamber is 310 °C, the column front pressure is 22.97psi, the temperature of the detector is 320 °C, and the column oven is heated according to the set program: the initial temperature is 50 °C, the residence time at this initial temperature is 3min, and then it is heated to 200 °C at a heating rate of 10 °C / min, and the residence time at this temperature is 10min.

[0061] The analysis conditions of the liquid chromatography are as follows: an ultraviolet detector (detection wavelength 280nm), a TM.X-C18 chromatographic column (4μm, 4.6×250mm), the column temperature is 35 °C, the mobile phase is methanol and water (3:2), the injection volume is 10 μL, and the flow rate is 1 mL.

[0062] 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.

[0063] Table 1 Catalytic performance of the Ru-based catalysts in Examples 1-3 and Comparative Examples 1-6

[0064] III. Stability test The stability test of the shaped Ru-based catalyst of Example 1 was carried out in a reaction kettle, 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 6MPa, 2,4-DNT was catalytically hydrogenated to 2,4-HTDA.

[0065] Table 2 Catalytic performance results of the Ru-based catalyst of Example 3 after being reused 10 times

[0066] Table 2 shows that after the shaped Ru-based catalyst of Example 1 was reused 10 times, the conversion rate of 2,4-DNT was still as high as 99.9%, the selectivity of 2,4-HTDA was 88.5%, and other by-products included 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.

[0067] Figure 3 For the TEM characterization results, through Figure 3 a- Figure 3As can be seen from d, the forming process using pseudo-boehmite binding and mechanical pressing can effectively maintain the initial characteristics of the catalyst. The particle size of the metal particles 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% are achieved in the first reaction. Secondly, through Figure 3 e and Figure 3 f, it can be seen that the formed catalyst in Example 1 exhibits excellent cycle stability. After 10 reactions, only slight particle coarsening of 2-4 nm occurs, the conversion rate 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.

[0068] 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 at 3.09 / 0.74 wt% from 3.20 / 0.80 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 cycle stability by optimizing the catalyst structure, making it have both excellent initial activity and long-term use performance.

[0069] 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 in the protection scope of the present invention.

Claims

1. A Ru-based catalyst molding method for catalyzing the 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 to obtain a mixed powder; then the adhesive is added, stirred until it is in a gelatinous state, and then extruded into strips, cut into sections, dried, calcined, and reduced with hydrogen to obtain a shaped Ru-based catalyst; The first catalyst precursor is one of Ru2(CO3)3 / carrier and Ru2(CO3)3-Rh2(CO3)3 / carrier; The second catalyst precursor is RuO x / Carrier, RuO x -RhO x / One of the vectors.

2. A Ru-based catalyst molding method for catalyzing the hydrogenation of 2,4-dinitrotoluene to prepare 1-methyl-2,4-cyclohexanediamine according to claim 1, characterized in that: The first catalyst precursor is Ru2(CO3)3-Rh2(CO3)3 / carrier, wherein the mass ratio of Ru to Rh is 1:(0.1-10), and the second catalyst precursor is RuO x -RhO x / carrier, wherein the mass ratio of Ru to Rh is 1:(0.1~10).

3. A Ru-based catalyst molding method for catalyzing the hydrogenation of 2,4-dinitrotoluene to prepare 1-methyl-2,4-cyclohexanediamine according to claim 2, characterized in that: The preparation method of the first catalyst precursor Ru2(CO3)3-Rh2(CO3)3 / carrier comprises the following steps: (1) First, dry the carrier at 60-120°C for 1-24 hours, then grind it, pass it through a 200-mesh sieve, and then put it into a dryer for later use; (2) adding a RuCl3 aqueous solution with a concentration of 0.1 to 2.0 mol / L and a RhCl3 aqueous solution with a concentration of 0.1 to 2.0 mol / L to a container containing a carrier, and immersing the carrier for 1 to 24 h under strong stirring to obtain a solution A; (3) Add the carbonate aqueous solution dropwise to solution A. After the addition is complete, age the solution for 1 to 24 hours. (4) filtering the mixed solution obtained in step (3) and drying at 60 to 120° C. for 1 to 24 hours; (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.

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

5. A Ru-based catalyst molding method for catalyzing the hydrogenation of 2,4-dinitrotoluene to prepare 1-methyl-2,4-cyclohexanediamine according to claim 3, characterized in that: In step (3), the concentration of the carbonate aqueous solution is 0.1-2 mol / L, and the carbonate is one of sodium carbonate, ammonium carbonate and potassium carbonate.

6. A Ru-based catalyst molding method for catalyzing the hydrogenation of 2,4-dinitrotoluene to prepare 1-methyl-2,4-cyclohexanediamine according to claim 2, characterized in that: The second catalyst precursor RuO x -RhO x The preparation method of the carrier is as follows: weigh the first catalyst precursor Ru2(CO3)3-Rh2(CO3)3 / carrier, place it in a muffle furnace, calcine it at 200-700°C for 1-8h, and then cool it to room temperature to obtain the second catalyst precursor RuO x -RhO x / vector.

7. The Ru-based catalyst molding method for catalyzing the hydrogenation of 2,4-dinitrotoluene to prepare 1-methyl-2,4-cyclohexanediamine according to claim 1, characterized in that: The binder is pseudo-boehmite or a mixture of pseudo-boehmite and aluminum sol, and the pseudo-boehmite and the aluminum sol are mixed in a mass ratio of 1: (0-10).

8. The Ru-based catalyst molding method for catalyzing the 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, and the binder accounts for 20-30% of the total mass of the mixed powder. The particle size of the mixed powder is 100-300 meshes.

9. The Ru-based catalyst molding method for catalyzing the hydrogenation of 2,4-dinitrotoluene to prepare 1-methyl-2,4-cyclohexanediamine according to claim 1, characterized in that: The adhesive is a nitric acid aqueous solution with a concentration of 1-10 wt%, the mass of nitric acid in the nitric acid aqueous solution accounts for 30-50% of the sum of the mass of the mixed powder and the 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.

10. The Ru-based catalyst molding method for catalyzing the hydrogenation of 2,4-dinitrotoluene to prepare 1-methyl-2,4-cyclohexanediamine according to claim 1, characterized in that: The unformed catalyst after cutting is vacuum dried at 105°C for 12 hours, and then placed in a fixed bed reactor with an inner diameter of 10 mm for calcination. The temperature is increased under high-purity nitrogen purge at a heating rate of 10°C / min. After reaching the hydrogen reduction temperature, the temperature is maintained constant. The hydrogen reduction temperature is 400°C. High-purity hydrogen is introduced to reduce the catalyst precursor. The hydrogen pressure is 0.5MPa and the reduction time is 4 hours. 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 to 10 mm and the strength is not less than 45N / cm.

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