A supported ruthenium-based catalyst, its preparation method and application

Abstract

This invention relates to the field of catalyst technology, providing a supported ruthenium-based catalyst, its preparation method, and its application. The supported ruthenium-based catalyst provided by this invention comprises a support and an active metal Ru; the active metal Ru is dispersed on the surface of the support in the form of elemental atom clusters and Ru oxide clusters; the elemental Ru atom clusters are dispersed around the Ru oxide clusters; the support is an oxygen-containing support. The supported ruthenium-based catalyst provided by this invention exhibits high hydrogenation selectivity and activity. When applied to the selective hydrogenation reduction reaction of 2,4-dinitroaniline, it can effectively improve the conversion rate of the reactants and the selectivity of the target product, 4-nitro-o-phenylenediamine. The preparation method provided by this invention is simple, easy to operate, and suitable for large-scale production.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and in particular to a supported ruthenium-based catalyst, its preparation method, and its application. Background Technology

[0002] Aromatic amines are important intermediates and raw materials in organic synthesis. They have wide applications in pharmaceuticals, pesticides, synthetic resins, rubber additives, surfactants, textile auxiliaries, chelating agents, polymers, flame retardants, dyes, organic light-emitting materials, and other fields, and occupy a very important position in the development of modern organic chemical industry.

[0003] Aromatic amines are generally prepared through methods such as the condensation amination of nitrogen-containing compounds or the reduction of aromatic nitro compounds. Because condensation amination reactions are complex and often have low yields, the reduction of aromatic nitro compounds is commonly used in fine chemical production to prepare aromatic amines. This method has advantages such as simple operation, readily available raw materials, and low cost. Methods for preparing aromatic amines by reducing aromatic nitro compounds mainly include catalytic hydrogenation reduction, CO reduction, metal reduction, sodium sulfide reduction, metal hydride reduction, hydrazine hydrate reduction, electrochemical reduction, biological methods, and photocatalysis. Among these, the CO reduction method suffers from catalyst deactivation; metal reduction and sodium sulfide reduction methods cause significant pollution; the metal hydrides and hydrazine hydrate used in metal hydride reduction and hydrazine hydrate reduction methods are costly; the promotion and application of electrochemical reduction are limited by electrolytic cells and electrode materials; and biological and photocatalytic reduction methods are currently only at the laboratory stage. In comparison, catalytic hydrogenation reduction has attracted much attention due to its relatively mature process, environmental friendliness, and high industrial application value. The catalytic hydrogenation reduction method for producing aromatic amines uses metals such as Ni, Pd, Pt, and Au, their alloys, oxides, or other non-metallic materials as catalysts, and H2 as the main reducing agent to reduce aromatic nitro compounds to aromatic amine compounds under certain temperature and pressure conditions.

[0004] Compared to Fe, Ni, Au, Pd, and Pt-based catalysts, ruthenium-based catalysts are simpler to prepare, exhibit better selective hydrogenation performance for single sterically hindered nitro groups in dinitro aromatic compounds, and require relatively mild hydrogenation conditions, making them the most widely used. However, the hydrogenation selectivity and activity of current ruthenium-based catalysts are still relatively poor. Summary of the Invention

[0005] In view of this, the present invention provides a supported ruthenium-based catalyst, its preparation method, and its application. The supported ruthenium-based catalyst provided by the present invention exhibits high hydrogenation selectivity and activity. When applied to the selective hydrogenation reduction reaction of 2,4-dinitroaniline, it can effectively improve the conversion rate of reactants and the selectivity of the target product.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] A supported ruthenium-based catalyst includes a support and an active metal Ru; the active metal Ru is dispersed on the surface of the support in the form of elemental atom clusters and Ru oxide clusters; the elemental Ru atom clusters are dispersed around the Ru oxide clusters; the support is an oxygen-containing support.

[0008] Preferably, a single Ru atom cluster contains 2 to 3 Ru atoms; the Ru oxide cluster includes a RuO2 (111) facet and a RuO2 (200) facet; the size of the Ru oxide cluster is 1.24 ± 0.04 nm; and the molar ratio of Ru atom to Ru oxide in the supported ruthenium-based catalyst is 1 to 2:1.

[0009] Preferably, the supported ruthenium-based catalyst has a molecular weight of 1926–1974 cm⁻¹. -1 2008~2012cm -1 and 2021~2084cm -1 The wavenumbers exhibit bridge adsorption peaks, twin adsorption peaks, and end adsorption peaks for CO, all within the range of 3000–3500 cm⁻¹. -1 The wavenumber has a stretching vibration peak of -OH or -NH2.

[0010] Preferably, the Ru oxides in the Ru oxide cluster include two types, with the first type of Ru oxide having a reduction temperature of 430°C and the second type of Ru oxide having a reduction temperature of 700°C; the molar ratio of the first type of Ru oxide to the second type of Ru oxide is 1.5 to 2:1.

[0011] Preferably, the carrier includes one or more of alumina, silica, titanium dioxide, and zeolite molecular sieves.

[0012] Preferably, the alumina is α-alumina or γ-alumina; when the support is α-alumina, the cell parameters of the support in the supported ruthenium-based catalyst are:

[0013] Preferably, the loading of the active metal Ru is 0.01 to 2 wt% of the support, based on the total mass of Ru atoms in the supported ruthenium-based catalyst and Ru elements in Ru oxides.

[0014] This invention also provides a method for preparing the supported ruthenium-based catalyst described above, comprising the following steps:

[0015] Ru salt, polyvinylpyrrolidone, water, organic solvent and carrier are mixed, the pH of the resulting mixture is adjusted to 4-8, and then a reduction reaction is carried out under CO gas to obtain a suspension; the organic solvent includes one or more of alcohol solvents, amide solvents, pyrrolidone solvents, sulfoxide solvents and furan solvents;

[0016] The suspension was subjected to a static reaction under solvothermal conditions to obtain a solid product.

[0017] The solid product was calcined under a protective atmosphere to obtain the supported ruthenium-based catalyst.

[0018] Preferably, the Ru salt includes one or more of RuCl3, Ru(acac)3, Ru(Ac)3 and Ru(NO)(NO3)3;

[0019] The organic solvent includes one or more of ethylene glycol, N,N-dimethylformamide, N,N-dimethylacetamide, N,N-diethylformamide, N-methylpyrrolidone, N-ethylpyrrolidone, dimethyl sulfoxide, and tetrahydrofuran.

[0020] Preferably, the reduction reaction is carried out at a temperature of 60–90°C for a time of 2–6 hours.

[0021] The static reaction under the solvothermal conditions is carried out at a temperature of 120–180°C for a time of 10–16 h.

[0022] The calcination temperature is 600–800℃, the time is 4–6 hours, and the heating rate to the calcination temperature is 2–5℃ / min; the protective atmosphere is nitrogen.

[0023] The present invention also provides the application of the supported ruthenium-based catalyst described in the above scheme or the supported ruthenium-based catalyst prepared by the preparation method described in the above scheme in the selective hydrogenation of dinitro aromatics; wherein one of the nitro groups in the dinitro aromatics contains other substituents at the ortho position.

[0024] This invention provides a supported ruthenium-based catalyst, comprising a support and an active metal Ru; the active metal Ru is dispersed on the surface of the support in the form of elemental Ru atom clusters and Ru oxide clusters; the elemental Ru atom clusters are dispersed around the Ru oxide clusters; the support is an oxygen-containing support. In the supported ruthenium-based catalyst provided by this invention, the active metal Ru exists in the form of Ru elemental atom clusters and Ru oxide clusters, and the specific dispersion state and position between the Ru elemental atom clusters and Ru oxide clusters can improve the selectivity and catalytic activity of the catalyst. Furthermore, the supported ruthenium-based catalyst provided by this invention has a low loading of active metal Ru, which is beneficial for reducing costs.

[0025] This invention also provides a method for preparing the supported ruthenium-based catalyst described above, comprising the following steps: mixing a Ru precursor salt, polyvinylpyrrolidone, water, an organic solvent, and a support; adjusting the pH of the resulting mixture to 4-8; and then carrying out a reduction reaction under CO gas protection to obtain a suspension; wherein the organic solvent includes one or more of alcohol solvents, amide solvents, pyrrolidone solvents, sulfoxide solvents, and furan solvents; subjecting the suspension to a static reaction under hydrothermal conditions to obtain a solid product; and calcining the solid product to obtain the supported ruthenium-based catalyst. This invention first involves a reduction reaction under CO conditions to reduce Ru ions to Ru atoms. Under hydrothermal conditions, the organic solvent is decomposed into substances such as CO, short-chain alkylamines, aldehydes, nitrogen oxides, alcohols, and ethylene. These substances act as capping agents, controlling the particle size and crystal facets of Ru atom clusters and Ru oxide clusters. Finally, calcination causes a secondary dispersion of the active metal Ru, resulting in a specific dispersion state and position between the Ru elemental atom clusters and Ru oxide clusters, thereby obtaining a supported ruthenium-based catalyst with good selectivity and activity. Furthermore, the preparation method provided by this invention is simple, easy to operate, and suitable for large-scale production.

[0026] This invention also provides the application of the supported ruthenium-based catalyst described above in the selective hydrogenation of dinitro aromatic hydrocarbons, wherein one of the nitro groups in the dinitro aromatic hydrocarbon contains other substituents at the ortho position. In the embodiments of this invention, 2,4-dinitroaniline was used as the reactant to test the activity and selectivity of the catalyst. The catalytic principle of this invention is explained below using 2,4-dinitroaniline as an example: The -NO2 on the benzene ring of 2,4-dinitroaniline is in an electron-deficient state. Due to steric hindrance, 4-NO2 is more easily adsorbed, thus easily generating the byproduct 2-nitro-p-phenylenediamine in the reduction reaction. In this invention, the supported ruthenium-based catalyst is used in the selective hydrogenation reaction of 2,4-dinitroaniline. The active metal Ru in the catalyst is dispersed in the form of elemental atom clusters or Ru oxide clusters, with the elemental atom clusters dispersed around the Ru oxide clusters. The Ru in the Ru oxide clusters... δ+ Being in an electron-deficient state, it is not easy to adsorb -NO2, thus avoiding the formation of byproducts; at the same time, the surrounding Ru elemental atom clusters serve to activate hydrogen, providing suitable activated hydrogen species, which provides conditions for the formation of the target product 4-nitro-o-phenylenediamine, effectively improving the selectivity of the target product while ensuring the conversion rate of reactants. Attached Figure Description

[0027] Figure 1The images show AC-STEM images of a supported ruthenium-based catalyst, 0.01% Ru / α-Al₂O₃ (DMF 30 mL + EG 20 mL). Images a and b are AC-STEM images of 0.01% Ru / α-Al₂O₃ (DMF 30 mL + EG 20 mL); image c shows the RuO₂ content in 0.01% Ru / α-Al₂O₃ (DMF 30 mL + EG 20 mL). x Cluster size distribution;

[0028] Figure 2 HRTEM image of 0.01% Ru / α-Al2O3 (DMF 30 mL + EG 20 mL) supported ruthenium-based catalyst;

[0029] Figure 3 XRD patterns of the supported ruthenium-based catalyst 0.01% Ru / α-Al2O3 (DMF 30mL + EG 20mL) and the α-Al2O3 support;

[0030] Figure 4 XPS spectra of the supported ruthenium-based catalyst 0.01% Ru / α-Al2O3 (DMF 30 mL + EG 20 mL);

[0031] Figure 5 H2-TPR spectrum of 0.01% Ru / α-Al2O3 (DMF 30mL + EG 20mL) supported ruthenium-based catalyst;

[0032] Figure 6 CO-DRIFTS spectrum of 0.01% Ru / α-Al2O3 (DMF 30mL + EG 20mL) supported ruthenium-based catalyst;

[0033] Figure 7 The FT-IR spectrum of the supported ruthenium-based catalyst 0.01% Ru / α-Al2O3 (DMF 30 mL + EG 20 mL). Detailed Implementation

[0034] This invention provides a supported ruthenium-based catalyst, comprising a support and an active metal Ru; the active metal Ru is dispersed on the surface of the support in the form of elemental atom clusters and Ru oxide clusters; the elemental Ru atom clusters are dispersed around the Ru oxide clusters; the support is an oxygen-containing support.

[0035] In this invention, a single Ru elemental atom cluster preferably contains 2 to 3 Ru atoms; the Ru oxide cluster includes a RuO2 (111) facet and a RuO2 (200) facet; the Ru oxide cluster (RuO xThe size of the ruthenium oxide is preferably 1.24 ± 0.04 nm; the molar ratio of Ru elemental atoms to Ru oxide in the supported ruthenium-based catalyst is preferably 1 to 2:1, more preferably 1 to 1.5:1; in this invention, the Ru oxide is formed by the coordination of some active metal Ru with oxygen atoms on the surface of the support, and the Ru in the Ru oxide is in the form of Ru... 4+ It exists in the form of; in this invention, the metal in the Ru oxide undergoes electron transfer with the support, and Ru is in an electron-deficient state.

[0036] In this invention, the supported ruthenium-based catalyst has a molecular weight of 1926–1974 cm⁻¹. -1 2008~2012cm -1 and 2021~2084cm -1 The wavenumbers exhibit bridge adsorption peaks, twin adsorption peaks, and end adsorption peaks for CO, all within the range of 3000–3500 cm⁻¹. -1 The wavenumber has a stretching vibration peak of -OH or -NH2.

[0037] In this invention, the Ru oxides in the Ru oxide clusters are divided into two categories. The first category of Ru oxides is reduced at a temperature of 430°C (denoted as RuO). x (430℃); the reduction temperature of the second type of Ru oxide is 700℃ (denoted as RuO). x (700℃); the molar ratio of the first type of Ru oxide and the second type of Ru oxide is preferably 1.5 to 2:1, more preferably 1.6 to 1.8:1. In this invention, the strength of the bond between the Ru oxide and the support affects the MSI. Different interactions between the Ru oxide and the support result in a stronger interaction, making it less likely to be reduced, and thus requiring a higher reduction temperature.

[0038] In this invention, the carrier preferably comprises one or more of alumina, silica, titanium dioxide, and zeolite molecular sieves; the alumina is preferably α-alumina or γ-alumina; the silica is preferably mesoporous silica, and in a specific embodiment of this invention, the silica is preferably XFF31; the titanium dioxide is preferably P. 25 The silica-to-alumina ratio of the zeolite molecular sieve is preferably not less than 100, more preferably 100-200, and even more preferably 120; specifically, the zeolite molecular sieve is preferably ZSM-5 or HZSM-5. In a specific embodiment of the present invention, the support is most preferably α-alumina.

[0039] In this invention, the Ru oxide in the Ru oxide cluster is incorporated into the surface of the alumina support, thereby increasing the cell parameters of the support; when the support is α-alumina, the cell parameters of the support in the ruthenium-based supported catalyst are preferably: More preferably In a specific embodiment of the present invention, Ru elemental atom clusters and Ru oxide clusters are mainly dispersed on the Al2O3(012) support surface, and the interplanar spacing of the Al2O3(012) support surface is preferably 0.34 to 0.35 nm.

[0040] In this invention, the loading of the active metal Ru is preferably 0.01 to 2 wt% of the support mass, more preferably 0.05 to 1.5 wt%, and even more preferably 0.1 to 1 wt%, based on the total mass of Ru elemental atoms in the supported ruthenium-based catalyst and Ru element in Ru oxide.

[0041] This invention also provides a method for preparing the supported ruthenium-based catalyst described above, comprising the following steps:

[0042] Ru salt, polyvinylpyrrolidone, water, organic solvent and carrier are mixed, the pH of the resulting mixture is adjusted to 4-8, and then a reduction reaction is carried out under CO gas to obtain a suspension; the organic solvent includes one or more of alcohol solvents, amide solvents, pyrrolidone solvents, sulfoxide solvents and furan solvents;

[0043] The suspension was subjected to a static reaction under hydrothermal conditions to obtain a solid product.

[0044] The solid product was calcined to obtain the supported ruthenium-based catalyst.

[0045] This invention involves mixing a Ru precursor salt, polyvinylpyrrolidone, water, an organic solvent, and a carrier. The pH of the resulting mixture is adjusted to 4-8, and a reduction reaction is carried out under CO gas to obtain a suspension. In this invention, the Ru salt preferably includes one or more of RuCl3, Ru(acac)3, Ru(Ac)3, and Ru(NO)(NO3)3; the organic solvent preferably includes one or more of ethylene glycol (EG), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC), N,N-diethylformamide (DEF), N-methylpyrrolidone (NMP), N-ethylpyrrolidone (NEP), dimethyl sulfoxide (DMSO), and tetrahydrofuran (THF). In a specific embodiment of this invention, the organic solvent... The preferred agent is a mixed organic solvent of DMF and EG, wherein the volume ratio of DMF to EG in the mixed organic solvent is preferably 1–4:4–1, more preferably 3:2. The preferred amount ratio of Ru salt, water, and organic solvent is 0.005–0.20 g:5–20 mL:30–60 mL. The preferred mass ratio of polyvinylpyrrolidone to Ru salt is 0.05–0.1 g:0.1–0.2 g. The polyvinylpyrrolidone acts as a protective agent, protecting the shape stability of the metal particles and preventing the aggregation of nanoparticles, thereby stabilizing the reaction system. The amount ratio of Ru salt to support is determined based on the loading of the active metal Ru described in the above scheme.

[0046] In a specific embodiment of the present invention, it is preferable to first mix Ru salt and polyvinylpyrrolidone, then add water and stir to dissolve, followed by the addition of an organic solvent and a carrier, and then adjust the pH value of the resulting mixture; the pH value of the mixture is preferably adjusted to 4-8, more preferably to 6. In the present invention, the reagent used to adjust the pH value of the mixture is preferably sodium hydroxide solution or hydrochloric acid solution; since the solvents used in the hydrothermal process are mostly alkaline, adjusting the pH value of the mixture to 4-8 in the present invention can control the amount and strength of the capping agent generated during the hydrothermal process, thereby controlling the molar ratio of elemental Ru and Ru oxide on the surface of the resulting catalyst. In a specific embodiment of the present invention, the smaller the pH value (i.e., the greater the acidity), the greater the molar ratio of elemental Ru atoms and Ru oxide.

[0047] In this invention, the temperature of the reduction reaction is preferably 60-90°C, more preferably 70-80°C, and the time of the reduction reaction is preferably 2-6 hours, more preferably 3-5 hours; the reduction reaction is preferably carried out under stirring conditions.

[0048] After obtaining the suspension, the present invention preferably subjectes the suspension to a static reaction under hydrothermal conditions to obtain a solid product. In the present invention, the temperature for the static reaction under hydrothermal conditions is preferably 120–180°C, more preferably 130–150°C, and the reaction time is preferably 10–16 h, more preferably 12–15 h. The present invention preferably transfers the suspension to a Teflon liner and then subjects it to a static reaction under hydrothermal conditions. During the reduction reaction, most Ru ions are reduced to Ru atoms. During the hydrothermal process, Ru ions in the Ru salt are reduced, and the organic solvent decomposes. Amide solvents can generate CO and short alkylamines, alcohol hydroxyl groups in alcohol solvents are oxidized to aldehyde groups, pyrrolidone decomposes at high temperatures to produce CO, nitrogen oxides, and aldehyde groups, sulfoxides decompose to generate alcohols and aldehydes, and furans decompose to generate ethylene and aldehydes. These substances can all act as capping agents to control the size and crystal facets of Ru atom clusters and Ru oxide clusters, ensuring the stability of the catalyst metal structure. Furthermore, during the hydrothermal process, Ru atoms evaporate at high temperatures, and the oxygen-containing support captures the moving Ru atoms, controlling the synthesis of Ru oxide clusters. This results in an alternating distribution of Ru elemental atom clusters and Ru oxide clusters, with Ru elemental atom clusters only present around Ru oxide clusters. Additionally, different capping agents have varying capping strengths (i.e., the strength of the end-capping effect controlling Ru atom cluster growth), thus controlling the resulting Ru particle size and crystal facets differently. This leads to different interactions between the resulting Ru oxides and the support, resulting in Ru oxides with varying degrees of reduction susceptibility. In this invention, the Ru particle size and crystal facets significantly influence the adsorption state of dinitro aromatic hydrocarbons at the active sites on the catalyst surface, thereby affecting the distribution of catalytic activity and product selectivity. By controlling the particle size and crystal facets of the active component Ru through the aforementioned methods, this invention can significantly improve the activity and selectivity of the catalyst.

[0049] After the reaction is allowed to stand, the present invention preferably filters and dries the resulting reaction solution to obtain the solid product.

[0050] After obtaining the solid product, the present invention calcines the solid product to obtain the supported ruthenium-based catalyst. In the present invention, the solid product is preferably ground before calcination; the calcination temperature is preferably 600-800℃, more preferably 650-750℃, the calcination time is preferably 4-6h, more preferably 4.5-5.5h, and the heating rate to the calcination temperature is preferably 2℃ / min; the calcination is preferably carried out in a protective atmosphere, preferably nitrogen.

[0051] This invention also provides the application of the supported ruthenium-based catalyst described in the above-described scheme or the supported ruthenium-based catalyst prepared by the preparation method described in the above-described scheme in the selective hydrogenation of dinitro aromatic hydrocarbons, wherein one of the nitro groups in the dinitro aromatic hydrocarbon contains other substituents at the ortho position, preferably amino, vinyl, halogen substituents, hydroxyl or alkyl; wherein the nitro group in the dinitro aromatic hydrocarbon contains other substituents at the ortho position, and the catalyst of this invention can selectively hydrogenate the nitro group at the ortho position of the substituent, and has high catalytic activity and selectivity; in this invention, the dinitro aromatic hydrocarbon is preferably one or more of 2,4-dinitrotoluene, 2,4-dinitrophenol, 2,4-dinitrostyrene and 2,4-dinitroaniline, more preferably 2,4-dinitroaniline.

[0052] This invention does not impose special requirements on the specific conditions of the application; conditions well known to those skilled in the art can be used. In a specific embodiment of this invention, the supported ruthenium-based catalyst is preferably pressed into tablets, sieved, and then placed in a fixed-bed reactor. Hydrogen gas and a methanol solution of 2,4-dinitroaniline are then introduced to carry out a selective hydrogenation reduction reaction. The reaction temperature for the selective hydrogenation is preferably 80–150°C, more preferably 140°C; the reaction time is preferably 2–10 h, more preferably 4 h; and the space velocity is preferably 8–16 h⁻¹. -1 .

[0053] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0054] Example 1

[0055] Preparation of 0.01% Ru / α-Al2O3 (30 mL DMF + 20 mL EG):

[0056] Weigh 0.008 g Ru(acac)3 and 0.004 g PVP into a three-necked flask, add 10 mL of deionized water and stir to dissolve. Then add 30 mL of DMF and 20 mL of EG mixed organic solvent, and then add 2 g of α-Al2O3 powder. Adjust the pH to 6 with 0.025 g / mL HCl solution. Under the protection of CO gas, heat to 80 °C in an oil bath and stir at 300 rpm for 4 h to obtain a suspension.

[0057] The suspension was transferred to a 100 mL Teflon liner and allowed to react under hydrothermal conditions at 160 °C for 12 h. The reaction solution was then filtered, and the resulting solid product was washed with deionized water and ethanol solution and dried in a vacuum drying oven at 60 °C for 12 h. The dried solid was then calcined at 700 °C for 5 h at a heating rate of 2 °C / min under N2 protection. The resulting powder was ground to obtain a supported ruthenium-based catalyst powder, denoted as 0.01% Ru / α-Al2O3 (30 mL DMF + 20 mL EG).

[0058] Example 2

[0059] The other conditions were the same as in Example 1, except that the mass of Ru(acac)3 was changed to 0.016 g and the mass of PVP was changed to 0.008 g, resulting in a supported ruthenium-based catalyst powder, denoted as 0.02% Ru / α-Al2O3 (30 mL DMF + 20 mL EG).

[0060] Example 3

[0061] The other conditions were the same as in Example 1, except that the mass of Ru(acac)3 was changed to 0.032 g and the mass of PVP was changed to 0.016 g, resulting in a supported ruthenium-based catalyst powder, denoted as 0.04% Ru / α-Al2O3 (30 mL DMF + 20 mL EG).

[0062] Example 4

[0063] The other conditions were the same as in Example 1, except that the support was changed to ZSM-5 (Si / Al = 120) to obtain a supported ruthenium-based catalyst powder, denoted as 0.01% Ru / ZSM-5 (30 mL DMF + 20 mL EG).

[0064] Example 5

[0065] All other conditions are the same as in Example 1, except that the carrier is changed to TiO2 (type P). 25 The supported ruthenium-based catalyst powder was obtained and designated as 0.01% Ru / TiO2 (30 mL DMF + 20 mL EG).

[0066] Example 6

[0067] The other conditions were the same as in Example 1, except that the support was changed to SiO2 (model XFF31) to obtain a supported ruthenium-based catalyst powder, denoted as 0.01% Ru / SiO2 (30 mL DMF + 20 mL EG).

[0068] Example 7

[0069] The other conditions were the same as in Example 1, except that the organic solvent was changed to 50 mL DMSO to obtain a supported ruthenium-based catalyst powder, denoted as 0.01% Ru / α-Al2O3 (50 mL DMSO).

[0070] Example 8

[0071] The other conditions were the same as in Example 1, except that the organic solvent was changed to 50 mL NMP to obtain a supported ruthenium-based catalyst powder, denoted as 0.01% Ru / α-Al2O3 (50 mL NMP).

[0072] Example 9

[0073] The other conditions were the same as in Example 1, except that the organic solvent was changed to 50 mL THF to obtain a supported ruthenium-based catalyst powder, denoted as 0.01% Ru / α-Al2O3 (50 mL THF).

[0074] Example 10

[0075] The other conditions were the same as in Example 1, except that the pH of the solution was adjusted to 4 to obtain a supported ruthenium-based catalyst powder, denoted as 0.01% Ru / α-Al2O3 (30 mL DMF + 20 mL EG, pH = 4).

[0076] Example 11

[0077] The other conditions were the same as in Example 1, except that the pH of the solution was adjusted to 8 to obtain a supported ruthenium-based catalyst powder, denoted as 0.01% Ru / α-Al2O3 (30 mL DMF + 20 mL EG, pH = 8).

[0078] Catalyst characterization:

[0079] Figure 1 The image shows an AC-STEM image of a supported ruthenium-based catalyst, 0.01% Ru / α-Al₂O₃ (DMF 30 mL + EG 20 mL). Figure 1 Image a is an AC-STEM image of 0.01% Ru / α-Al₂O₃ (DMF 30 mL + EG 20 mL), showing Ru elemental atom clusters (yellow circles) and the presence of RuO₂ (200) planes; image b is an AC-STEM image of 0.01% Ru / α-Al₂O₃ (DMF 30 mL + EG 20 mL), showing RuO₂ (200) planes. x Morphology of the clusters; c represents the RuO content of 0.01% Ru / α-Al2O3 (DMF 30mL + EG 20mL). x Cluster size distribution. Figure 1 As can be seen from 'a', the active metal Ru on the catalyst surface is in the form of elemental atom clusters and RuO. xClusters are dispersed in an interwoven manner on the support surface, with elemental atomic clusters dispersed in RuO x The clusters are surrounded by Ru atoms, and the elemental Ru atom clusters contain 2 to 3 Ru atoms; Figure 1 From b and c, we can see that RuO x The cluster size is 1.24 ± 0.04 nm.

[0080] Figure 2 This is an HRTEM image of a supported ruthenium-based catalyst, 0.01% Ru / α-Al₂O₃ (DMF 30 mL + EG 20 mL). Figure 2 It can be seen that in a 0.01% Ru / Al2O3 (DMF 30mL + EG 20mL) catalyst, RuO x The cluster surface includes RuO2(111) and RuO2(200) surfaces, and the metal is mainly dispersed on the Al2O3(012) support surface.

[0081] Figure 3 XRD patterns of the supported ruthenium-based catalyst 0.01% Ru / α-Al₂O₃ (DMF 30 mL + EG 20 mL) and the α-Al₂O₃ support. Figure 3 It can be seen that the catalyst support after organic solvent treatment and high-temperature calcination can be classified into various crystal planes of α-Al₂O₃. However, due to the incorporation of Ru metal oxide into the α-Al₂O₃ framework, the cell volume increases to a certain extent. The cell parameters are: a = 4.76087 Å, b = 4.76087 Å, c = 12.99808 Å, V = 255.14 Å. 3 The primitive unit cell parameters of α-Al₂O₃ are: a = 4.76028 Å, b = 4.76028 Å, c = 12.99443 Å, V = 255.01 Å. 3 .

[0082] Figure 4 XPS spectra of a supported ruthenium-based catalyst 0.01% Ru / α-Al₂O₃ (DMF 30 mL + EG 20 mL). Figure 4 It can be seen that in the XPS Ru 3p orbital pattern corresponding to the catalyst, the metallic Ru atom cluster and RuO x The molar ratio of the clusters is 1.01. The catalyst surface contains a similar abundance of elemental Ru atoms and RuO. x During catalytic reactions, RuO clusters... x The clusters can effectively prevent the adsorption of 4-NO2, while an equal amount of Ru elemental atom clusters provide appropriate activated hydrogen species, ensuring that 2-NO2 is reduced to the target product under the action of the neighboring group effect, without hydrogenating 4-NO2 to generate byproducts.

[0083] Figure 5The image shows the H2-TPR spectrum of a supported ruthenium-based catalyst, 0.01% Ru / α-Al2O3 (DMF 30 mL + EG 20 mL). Figure 5 It can be seen that the catalyst surface contains two types of metal oxides, which can be reduced at 430℃ and 700℃ respectively (i.e., RuO). x (430℃) and RuO x (700℃)), and it can be seen from the peak area fitting that RuO x (430℃) / RuO x The molar ratio (700℃) is 1.5:1.

[0084] Figure 6 The CO-DRIFTS spectrum of the supported ruthenium-based catalyst 0.01% Ru / α-Al₂O₃ (DMF 30 mL + EG 20 mL) is shown. Figure 6 It can be seen that the catalyst is at 1926 cm⁻¹ -1 2008cm -1 and 2084cm -1 The wavenumber exhibits bridging adsorption peaks, twinning adsorption peaks, and end adsorption peaks for Ru on CO.

[0085] Figure 7 The image shows the FT-IR spectrum of a supported ruthenium-based catalyst, 0.01% Ru / α-Al₂O₃ (DMF 30 mL + EG 20 mL). Figure 7 It can be seen that the catalyst is in the range of 3000-3500 cm⁻¹ -1 The wavenumber has a stretching vibration peak of -OH or -NH2.

[0086] Catalytic performance test:

[0087] 1. Using 2,4-dinitroaniline as a substrate: Supported ruthenium-based catalyst powder was compressed into tablets and sieved to a mesh size of 40-60. 0.3 g of the tablets was placed in a quartz tube of a fixed-bed reactor. High-purity hydrogen gas (99.99% by volume) and a methanol solution containing 0.01 g / mL of dissolved 2,4-dinitroaniline were introduced. The reaction was carried out at 140℃ for 4 hours. Samples were taken at 4 hours, and the mixture was cooled. Gas chromatography was used to analyze the resulting samples, and the conversion rate and selectivity of each product were calculated.

[0088] The conversion rate and selectivity are calculated as follows:

[0089]

[0090]

[0091] The test results for conversion rate and selectivity are shown in Table 1.

[0092] Table 1. Catalytic performance test results for the selective hydrogenation reaction of 2,4-dinitroaniline.

[0093]

[0094] Table 1 shows that when the Ru loading is 0.01%, the catalyst exhibits the highest selectivity for the target product, 4-nitro-o-phenylenediamine, reaching 100%. With increasing Ru loading, Ru cannot form a highly dispersed state on the support surface, and Ru elemental clusters and RuO... x The increased cluster size leads to the adsorption of -NO2 on the benzene ring of the substrate molecule. Furthermore, due to steric hindrance and neighboring group effects, the selectivity of the target product, 4-nitro-o-phenylenediamine, decreases. Similarly, as seen in Examples 7-9, the selectivity of the target product prepared by the 0.01% Ru / α-Al2O3 catalyst in 50 mL of DMSO, NMP, and THF is slightly reduced. This may be because the capping agent has a weaker capping effect on the metal particle size, resulting in the adsorption of Ru elemental clusters and RuO2. x As the clusters increase in size, the adsorption effect is enhanced, and the byproduct 2-nitro-p-phenylenediamine is generated, but the selectivity of the target product can still be maintained at around 80%. Furthermore, as can be seen from Examples 4-6 and Examples 10-11, catalysts prepared using different supports or under different pH conditions all exhibit good selectivity and activity.

[0095] 2. Using other dinitroaromatic compounds as substrates: The other conditions were the same as those for the catalytic activity test when using 2,4-dinitroaniline as substrate, except that the reactants were replaced with 2,4-dinitrophenol, 2,4-dinitrotoluene, or 2,4-dinitrostyrene. The catalyst used was 0.01% Ru / α-Al2O3 (DMF 30 mL + EG 20 mL) prepared in Example 1. The test results are shown in Table 2.

[0096] Table 2 0.01% Ru / α-Al2O3

[0097] Catalytic performance test results of (DMF 30mL + EG 20mL) catalyst for selective hydrogenation of other dinitro aromatics

[0098]

[0099] Table 2 shows that the conversion and target product selectivity of the 0.01% Ru / α-Al₂O₃ (DMF 30 mL + EG 20 mL) catalyst varied to different degrees when used for the selective hydrogenation of other dinitro aromatics. This may be because the electron-donating capabilities of the substituents at the -NO₂ position on the benzene ring of the substrate molecule differ; dinitro compounds with stronger electron-donating capabilities exhibit higher selectivity for the selective hydrogenation to the target product. Overall, the supported ruthenium-based catalyst of this invention exhibits good catalytic activity and selectivity for various dinitro aromatic compounds.

[0100] Comparative Example 1

[0101] 0.01% Ru / α-Al2O3 (chemical reduction method): Set up a reflux condenser in a 100mL three-necked round-bottom flask. Add 0.020g PVP, 2mL deionized water, and 15mL anhydrous ethanol at room temperature. Turn on magnetic stirring and add 27μL RuCl3 solution (Ru mass concentration is 0.0037g / mL) after PVP dissolves. Add 0.025g / mL NaOH solution dropwise to the resulting solution to adjust the pH to 6. Add 5mL of formaldehyde solution with a mass fraction of 37%–40% using a pipette and start heating under reflux. When the reflux temperature reaches 85℃, add 1g α-Al2O3 powder and continue heating under reflux for 3h.

[0102] After reflux, the obtained catalyst was filtered and washed, and then dried under vacuum at 60°C for 6 hours. The dried catalyst was placed under N2 atmosphere and calcined at 300°C for 3 hours at a heating rate of 2°C / min. After cooling to room temperature, it was taken out to obtain a 0.01wt% Ru / α-Al2O3 catalyst.

[0103] Comparative Example 2

[0104] 0.01% Ru / α-Al2O3 (impregnation method): Weigh 1g α-Al2O3 and 0.004g PVP into a three-necked flask, add 50ml deionized water and stir well, then add 27μL RuCl3 solution (Ru mass concentration is 0.0037g / mL), adjust pH to 6 with 0.025g / mL HCl solution, stir at 600rpm for 18h at room temperature to obtain a suspension.

[0105] The suspension was filtered, washed with deionized water and ethanol solution, and dried in a vacuum drying oven at 60°C for 12 hours. The resulting dried solid was then calcined at 300°C for 3 hours at a heating rate of 2°C / min under N2 protection. The solid was then ground to obtain 0.01% Ru / α-Al2O3 (impregnation method) supported catalyst powder.

[0106] Comparative Example 3

[0107] 0.01% Ru / α-Al2O3(DMF 30mL+EG 20mL)-300: Weigh 0.008g Ru(acac)3 and 0.004g PVP into a three-necked flask, add 10mL deionized water and stir to dissolve, then add 30mL DMF and 20mL EG mixed organic solvent, then add 2g α-Al2O3 powder, adjust pH to 6 with 0.025g / mL HCl solution, heat to 80℃ in an oil bath under CO gas protection, and stir at 300rpm for 4h to obtain a suspension.

[0108] The suspension was transferred to a 100 mL Teflon liner and allowed to react under hydrothermal conditions at 160 °C for 12 h. The resulting reaction solution was filtered, and the solid product was washed with deionized water and ethanol solution. The solid product was then dried in a vacuum drying oven at 60 °C for 12 h. The dried solid was then calcined at 300 °C for 5 h at a heating rate of 2 °C / min under N2 protection. The resulting ruthenium-based catalyst was prepared by grinding and designated as 0.01% Ru / α-Al2O3(30 mL DMF + 20 mL EG)-300 powder.

[0109] Comparative Example 4

[0110] 0.01% Ru / α-Al2O3(DMF 30mL+EG 20mL)-900: Weigh 0.008g Ru(acac)3 and 0.004g PVP into a three-necked flask, add 10mL deionized water and stir to dissolve, then add 30mL DMF and 20mL EG mixed organic solvent, then add 2g α-Al2O3 powder, adjust pH to 6 with 0.025g / mL HCl solution, heat to 80℃ in an oil bath under CO gas protection, and stir at 300rpm for 4h to obtain a suspension.

[0111] The suspension was transferred to a 100 mL Teflon liner and allowed to react under hydrothermal conditions at 160 °C for 12 h. The resulting reaction solution was filtered, and the solid product was washed with deionized water and ethanol solution. The solid product was then dried in a vacuum drying oven at 60 °C for 12 h. The dried solid was then calcined at 900 °C for 5 h at a heating rate of 2 °C / min under N2 protection. The resulting powder was ground to obtain a 0.01% Ru / α-Al2O3 (30 mL DMF + 20 mL EG)-900 supported catalyst.

[0112] The catalysts prepared in Comparative Examples 1 to 4 were subjected to catalytic performance tests using the same methods and conditions as described in the "Catalytic Performance Test" section above, with 2,4-dinitroaniline as the substrate. The results are shown in Table 3, with data from Example 1 also included in Table 3 for comparison.

[0113] Table 3. Catalytic performance test results

[0114]

[0115] As shown in Table 3, in Comparative Example 1, the catalyst prepared by chemical reduction lacked the constraint of organic solvents on the size of Ru elemental clusters, resulting in the formation of Ru metal particles. This enhanced the adsorption of 4-NO2, leading to an increase in reactant conversion, but significantly reduced the selectivity of the target product and the formation of byproducts. In Comparative Example 2, the catalyst prepared by impregnation had poor loading and uneven metal distribution, resulting in increased reactant conversion, but significantly reduced the selectivity of the target product and the formation of byproducts. In Comparative Example 3, calcination at 300℃ prevented the metal from being secondary dispersed at an appropriate temperature, resulting in uneven metal distribution and increased reactant conversion, but significantly reduced the selectivity of the target product and the formation of byproducts. In Comparative Example 4, calcination at 900℃ caused the metal to agglomerate at high temperature, forming Ru metal particles. This enhanced the adsorption of 4-NO2, leading to increased reactant conversion, but significantly reduced the selectivity of the target product and the formation of byproducts.

[0116] The results of the above embodiments show that the supported ruthenium-based catalyst provided by the present invention comprises Ru elemental clusters and RuO. x Clusters, together with RuO, contribute to the optimal catalytic effect of the catalyst. Combining activity and characterization data, it can be seen that the metallic Ru elemental atom clusters and RuO... x The unique dispersion state and location of the clusters are the reason why the resulting catalyst exhibits excellent selectivity for the target product. The supported ruthenium-based catalyst provided by this invention has good catalytic performance, high conversion rate and selectivity, and has broad application prospects.

[0117] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A supported ruthenium-based catalyst, characterized in that, The system includes a support and an active metal Ru; the active metal Ru is dispersed on the surface of the support in the form of elemental atom clusters and Ru oxide clusters; the elemental Ru atom clusters are dispersed around the Ru oxide clusters; the support is an oxygen-containing support. The preparation method of the supported ruthenium-based catalyst includes the following steps: Ru salt, polyvinylpyrrolidone, water, organic solvent and carrier are mixed, the pH of the resulting mixture is adjusted to 4-8, and then a reduction reaction is carried out under CO gas to obtain a suspension; the organic solvent includes one or more of alcohol solvents, amide solvents, pyrrolidone solvents, sulfoxide solvents and furan solvents; The suspension was subjected to a static reaction under solvothermal conditions to obtain a solid product. The solid product was calcined under a protective atmosphere to obtain the supported ruthenium-based catalyst.

2. The supported ruthenium-based catalyst according to claim 1, characterized in that, Each Ru atom cluster contains 2 to 3 Ru atoms; the Ru oxide cluster includes a RuO2 (111) facet and a RuO2 (200) facet; the size of the Ru oxide cluster is 1.24 ± 0.04 nm; the molar ratio of Ru atom to Ru oxide in the supported ruthenium-based catalyst is 1 to 2:

1.

3. The supported ruthenium-based catalyst according to claim 1, characterized in that, The supported ruthenium-based catalyst was in the range of 1926–1974 cm⁻¹. -1 2008~2012 cm -1 and 2021~2084 cm -1 The wavenumbers exhibit bridge adsorption peaks, twin adsorption peaks, and end adsorption peaks for CO, all within the range of 3000–3500 cm⁻¹. -1 The wavenumber has a stretching vibration peak of -OH or -NH2.

4. The supported ruthenium-based catalyst according to claim 1 or 2, characterized in that, The Ru oxide clusters include two types of Ru oxides: the first type of Ru oxide is reduced at a temperature of 430°C, and the second type of Ru oxide is reduced at a temperature of 700°C; the molar ratio of the first type of Ru oxide to the second type of Ru oxide is 1.5 to 2:

1.

5. The supported ruthenium-based catalyst according to claim 1, characterized in that, The carrier includes one or more of alumina, silica, titanium dioxide, and zeolite molecular sieves.

6. The supported ruthenium-based catalyst according to claim 5, characterized in that, The alumina is α-alumina or γ-alumina; when the support is α-alumina, the cell parameters of the support in the supported ruthenium-based catalyst are: a = 4.76~4.77 Å, b = 4.76~4.77 Å, c = 12.99~13.01 Å, V = 255.15~255.16 Å. 3 .

7. The supported ruthenium-based catalyst according to claim 1, characterized in that, The loading of active metal Ru is 0.01 to 2 wt% of the support mass, based on the total mass of Ru atoms in the supported ruthenium-based catalyst and Ru elements in Ru oxide.

8. A method for preparing the supported ruthenium-based catalyst according to any one of claims 1 to 7, characterized in that, Includes the following steps: Ru salt, polyvinylpyrrolidone, water, organic solvent and carrier are mixed, the pH of the resulting mixture is adjusted to 4-8, and then a reduction reaction is carried out under CO gas to obtain a suspension; the organic solvent includes one or more of alcohol solvents, amide solvents, pyrrolidone solvents, sulfoxide solvents and furan solvents; The suspension was subjected to a static reaction under solvothermal conditions to obtain a solid product. The solid product was calcined under a protective atmosphere to obtain the supported ruthenium-based catalyst.

9. The preparation method according to claim 8, characterized in that, The Ru salt includes one or more of RuCl3, Ru(acac)3, Ru(Ac)3, and Ru(NO)(NO3)3; The organic solvent includes one or more of ethylene glycol, N,N-dimethylformamide, N,N-dimethylacetamide, N,N-diethylformamide, N-methylpyrrolidone, N-ethylpyrrolidone, dimethyl sulfoxide, and tetrahydrofuran; The reduction reaction is carried out at a temperature of 60-90℃ for 2-6 hours. The static reaction under the solvothermal conditions is carried out at a temperature of 120~180℃ for a time of 10~16h. The calcination temperature is 600~800℃, the time is 4~6h, and the heating rate to the calcination temperature is 2~5℃ / min; the protective atmosphere is nitrogen.

10. The application of the supported ruthenium-based catalyst according to any one of claims 1 to 6 or the supported ruthenium-based catalyst prepared by the preparation method according to any one of claims 7 to 9 in the selective hydrogenation of dinitro aromatics; wherein one of the nitro groups in the dinitro aromatics contains other substituents at the ortho position.

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