A sintering-resistant ruthenium-based catalyst, and a preparation method and application thereof

Abstract

The present application relates to a kind of sintering-resistant ruthenium-based catalyst, which is composed of main active component ruthenium, porous metal oxide carrier and adjuvant, and the weight percentage composition is as follows: 0.1% to 6% of metallic ruthenium, 0.15% to 9% of adjuvant, and the balance is porous metal oxide carrier;The adjuvant is any one or more than two kinds of mixture of magnesium, calcium and vanadium;The porous metal oxide carrier is any one or more than two kinds of mixture of cerium oxide, zirconium dioxide and titanium dioxide. At the same time, the preparation method and application of the catalyst are also disclosed. The preparation process of the present application is simple and easy to implement, the obtained catalyst has good sintering resistance and reaction stability, and the reaction activity is high, the selectivity of target product is good, and it can be used for the high-selectivity oxidation of multi-branched isononyl alcohol to produce multi-branched isononyl acid.

Description

Technical Field

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

[0002] Long-chain carboxylic acids are an important class of basic raw materials, widely used in the synthesis of fragrances, surfactants, plasticizers, pharmaceutical intermediates, lubricants, and metalworking fluids. Among them, carboxylic acids with two or more branched structures in their molecular structure are called multi-branched carboxylic acids. Due to their extremely low freezing point, good wettability, and emulsifying properties, they are often used in the production of fully synthetic refrigeration oils, cosmetics, environmentally friendly plasticizers, and other high-end new materials, with added value far exceeding that of linear and monobranched carboxylic acids with the same number of carbon atoms.

[0003] 3,5,5-Trimethyl-1-hexanoic acid (hereinafter referred to as multi-branched isononanoic acid) is one of the most widely used high-carbon carboxylic acids. Currently, the mainstream production technology obtains it through the oxidation of the corresponding aldehyde or alcohol. Patents CN 119822948 A, CN 114149313A, and CN 116375567 B report processes or catalysts for the oxidation of 3,5,5-trimethyl-1-hexanal to 3,5,5-trimethyl-1-hexanal. Inorganic bases such as sodium bicarbonate or isononanoates (lithium isononanoate, potassium isononanoate, sodium isononanoate, calcium isononanoate, or barium isononanoate) are often used as co-catalysts. The introduction of these complex components undoubtedly increases the difficulty of product separation and easily causes side reactions, reducing the selectivity of the target product. Although patents CN111470962 A and CN 114149313 B report a catalyst-free method for the direct oxidation of isononanal to isononanoic acid, the low reaction efficiency makes it difficult to improve the yield of the target product. Compared to the oxidation of aldehydes to produce acids, the direct oxidation of alcohols to obtain acids is much more difficult. Therefore, the catalyst systems for the oxidation of isononanol to isonononic acid reported in patents CN 112608227 B, CN112409144 B, and CN 112657510 A are extremely complex, even combining homogeneous and heterogeneous catalyst systems to achieve the conversion, making subsequent purification very troublesome. Patents CN115463657 A and CN 116899549 A report a supported Ru catalyst for the direct oxidation of isononanol to isonononic acid, which does not require the addition of any additional co-catalysts during the reaction. However, the catalyst preparation requires hydrothermal synthesis and a post-impregnation step, resulting in high preparation temperatures and a cumbersome process that is not conducive to process scale-up. Furthermore, the anions in the catalyst prepared by the impregnation method are difficult to remove, easily causing metal loss and reducing catalyst stability.

[0004] Metal sintering (agglomeration and growth) during the reaction is a common problem that prevents supported catalysts from meeting industrial standards. For supported ruthenium-based catalysts, metal sintering during the reaction is one of the main factors for catalyst deactivation, and this process is irreversible, so it cannot be restored after deactivation (J. Phys. Chem. C 2013, 117, 13108−13113). Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a ruthenium-based catalyst with improved sintering resistance and reaction stability.

[0006] Another technical problem to be solved by the present invention is to provide a method for preparing the sintering-resistant ruthenium-based catalyst.

[0007] The third technical problem to be solved by the present invention is to provide the application of this sintering-resistant ruthenium-based catalyst.

[0008] To address the aforementioned problems, the present invention provides a sintering-resistant ruthenium-based catalyst, characterized in that: the catalyst comprises a main active component ruthenium, a porous metal oxide support, and an additive, with the following weight percentage composition: 0.1%~6% ruthenium metal, 0.15%~9% additive, and the balance being the porous metal oxide support; the additive is any one or a mixture of two or more of magnesium, calcium, and vanadium; the porous metal oxide support is any one or a mixture of two or more of cerium oxide, zirconium dioxide, and titanium dioxide.

[0009] The catalyst is post-processed into granular, rod-shaped, spherical, strip-shaped, or flake-shaped forms by spray drying or extrusion.

[0010] The method for preparing a sintering-resistant ruthenium-based catalyst as described above is characterized by: firstly, weighing the components according to the specified proportions; then mixing an aqueous solution of ruthenium precursor with a weight percentage concentration of 0.3%~5%, an aqueous solution of auxiliary agent precursor with a weight percentage concentration of 0.1%~8%, and an aqueous solution of support precursor with a weight percentage concentration of 5%~40%, and heating the mixture to 40~96°C; slowly adding an aqueous solution of precipitant with a weight percentage concentration of 0.3%~30%; reacting for 3~18 hours; allowing the mixture to stand and age for 5~20 hours; vacuum filtering; washing with distilled water; drying at 60~120°C for 8~24 hours; and then calcining at 300~900°C for 3~8 hours to obtain the catalyst. The ruthenium precursor in the aqueous solution is any one of ruthenium trichloride hydrate, ruthenium nitrate, and hexaammonium trichloride ruthenium; the auxiliary agent precursor in the aqueous solution is any one or a mixture of two or more of magnesium nitrate, magnesium chloride, calcium nitrate, calcium chloride, ammonium metavanadate, sodium metavanadate, and potassium metavanadate; the carrier precursor in the aqueous solution is any one or a mixture of two or more of cerium nitrate, cerium sulfate, zirconium nitrate, zirconium sulfate, zirconium oxynitrate, zirconium oxychloride, and titanium sulfate; the precipitant in the aqueous solution is any one or a mixture of two or more of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, urea, and ammonia.

[0011] The application of the sintering-resistant ruthenium-based catalyst described above is characterized in that: in the presence of the ruthenium-based catalyst, a high-pressure autoclave reactor or a fixed-bed reactor is used to carry out the oxidation reaction of multi-branched isononanoic acid to generate multi-branched isononanoic acid.

[0012] The specific process of the oxidation reaction of multi-branched isononanol using a high-pressure autoclave reactor is as follows: First, the ruthenium-based catalyst is reduced and pretreated at 50-400℃ for 0.5-3 hours under a mixed atmosphere of 1%-5% hydrogen and 95%-99% nitrogen at atmospheric pressure; then, the mixed solution of ruthenium-based catalyst, multi-branched isononanol, and reaction solvent is reacted in an oxidizing atmosphere at 90-150℃ and 1-6MPa for 2-10 hours to obtain the multi-branched isononanoic acid product.

[0013] The specific process of the multi-branched isononanol oxidation reaction using a fixed-bed reactor is as follows: First, the ruthenium-based catalyst is reduced and pretreated for 0.5 to 3 hours at 50 to 400°C under a mixed atmosphere of 1% to 5% hydrogen and 95% to 99% nitrogen at atmospheric pressure; then, in an oxidizing atmosphere, a mixed solution of multi-branched isononanol and a reaction solvent is continuously fed into the reactor containing the ruthenium-based catalyst, and the reaction is carried out at a pressure of 1 to 6 MPa, a temperature of 90 to 150°C, and a liquid hourly space velocity of 0.1 to 2 h⁻¹. -1 The gas space velocity is 100~5000h -1 Under certain conditions, a continuous reaction was carried out to obtain a multi-branched isononanoic acid product.

[0014] The reaction solvent is any one of cyclohexane, isooctane, and 1-octane, and its weight percentage concentration in the mixed solution is 0-25%.

[0015] The oxidizing atmosphere is one of oxygen, air, or a mixture of oxygen / nitrogen in different proportions.

[0016] Gas mass flow meters and back pressure valves are used at the front and rear ends of the high-pressure autoclave reactor, respectively.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] 1. This invention develops a low-temperature, atmospheric-pressure, one-pot method for preparing ruthenium-based catalysts, eliminating the need for the traditional high-temperature, high-pressure hydrothermal synthesis of a support followed by impregnation with ruthenium metal. The synthesis method and process route are simpler and more suitable for industrial scale-up.

[0019] 2. The catalyst prepared by the co-precipitation method of this invention can better promote the anchoring and highly dispersed state of the active component ruthenium in the support, which is beneficial to improving the catalyst's resistance to sintering and reaction stability.

[0020] 3. The catalyst of this invention can stably operate the oxidation reaction in a high-pressure autoclave reactor or a fixed-bed reactor, and the continuous gas phase input / output more effectively ensures safety.

[0021] 4. The ruthenium-based catalyst of this invention has high reactivity and good selectivity for the target product, and can be used for the highly selective oxidation of multi-branched isononanol to produce multi-branched isononanoic acid.

[0022] 5. The preparation process of this invention is simple and easy to implement, and has the potential for industrial application. Attached Figure Description

[0023] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0024] Figure 1 This is a stability test diagram of catalyst H in Example 8 of the present invention.

[0025] Figure 2 The X-ray powder diffraction (XRD) patterns of the ruthenium-based catalyst prepared in this invention before and after use are shown. Detailed Implementation

[0026] A sintering-resistant ruthenium-based catalyst is disclosed, comprising ruthenium as the main active component, a porous metal oxide support, and additives. The weight percentage (g) composition is: 0.1%–6% ruthenium, 0.15%–9% additives, with the balance being the porous metal oxide support. The additives are any one or a mixture of two or more of magnesium, calcium, and vanadium. The porous metal oxide support is any one or a mixture of two or more of cerium oxide, zirconium dioxide, and titanium dioxide. The catalyst is post-processed into granular, rod-shaped, spherical, strip-shaped, or sheet-like forms using spray drying or extrusion processes.

[0027] Its preparation method:

[0028] First, weigh the ingredients according to the specified proportions. Then, mix the following: a ruthenium precursor aqueous solution with a weight percentage of 0.3%–5%, an auxiliary agent precursor aqueous solution with a weight percentage of 0.1%–8%, and a carrier precursor aqueous solution with a weight percentage of 5%–40%. Heat the mixture to 40–96°C, and slowly add a precipitant aqueous solution with a weight percentage of 0.3%–30%. After reacting for 3–18 hours, allow the mixture to stand for 5–20 hours. After vacuum filtration and washing with distilled water, dry the mixture at 60–120°C for 8–24 hours, and then calcine it at 300–900°C for 3–8 hours to obtain the catalyst.

[0029] Wherein: the ruthenium precursor in the ruthenium precursor aqueous solution is any one of ruthenium trichloride hydrate, ruthenium nitrate, and hexaammonium trichloride ruthenium; the auxiliary agent precursor in the auxiliary agent aqueous solution is any one or a mixture of two or more of magnesium nitrate, magnesium chloride, calcium nitrate, calcium chloride, ammonium metavanadate, sodium metavanadate, and potassium metavanadate; the carrier precursor in the carrier precursor aqueous solution is any one or a mixture of two or more of cerium nitrate, cerium sulfate, zirconium nitrate, zirconium sulfate, zirconium oxynitrate, zirconium oxychloride, and titanium sulfate; and the precipitant in the precipitant aqueous solution is any one or a mixture of two or more of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, urea, and ammonia.

[0030] Application of a sintering-resistant ruthenium-based catalyst: In the presence of this ruthenium-based catalyst, a high-pressure autoclave or fixed-bed reactor is used to carry out the oxidation reaction of multi-branched isononanoic acid to produce multi-branched isononanoic acid.

[0031] The specific process for the oxidation of multi-branched isononanol using a high-pressure autoclave reactor is as follows: First, the ruthenium-based catalyst is reduced and pretreated for 0.5–3 hours at 50–400°C under a mixed atmosphere of 1%–5% hydrogen and 95%–99% nitrogen at atmospheric pressure. Then, the mixed solution of the ruthenium-based catalyst, multi-branched isononanol, and reaction solvent is reacted for 2–10 hours in an oxidizing atmosphere at 90–150°C and 1–6 MPa to obtain the multi-branched isononanoic acid product. Gas mass flow meters and back pressure valves are used at the front and rear ends of the high-pressure autoclave reactor to ensure continuous gas entry and exit.

[0032] The specific process of the oxidation reaction of multi-branched isononanol using a fixed-bed reactor is as follows: First, a ruthenium-based catalyst is reduced and pretreated for 0.5 to 3 hours at 50 to 400 °C under a mixed atmosphere of 1% to 5% hydrogen and 95% to 99% nitrogen at atmospheric pressure. Then, in an oxidizing atmosphere, a mixed solution of multi-branched isononanol and a reaction solvent is continuously fed into the reactor containing the ruthenium-based catalyst, and the reaction is carried out at a pressure of 1 to 6 MPa, a temperature of 90 to 150 °C, and a liquid hourly space velocity of 0.1 to 2 h⁻¹. -1 The gas space velocity is 100~5000h -1 Under certain conditions, a continuous reaction was carried out to obtain a multi-branched isononanoic acid product.

[0033] The reaction solvent is any one of cyclohexane, isooctane, and 1-octane, with a weight percentage concentration of 0-25% in the mixed solution. The oxidizing atmosphere is one of oxygen, air, or a mixture of oxygen / nitrogen in different proportions, with air being preferred.

[0034] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0035] Example 1

[0036] 148.3 g of cerium nitrate hexahydrate was dissolved in 600 g of water, 6.3 g of magnesium nitrate hexahydrate was dissolved in 100 g of water, 1.7 g of ruthenium trichloride hydrate (Ru content 38.7%) was dissolved in 100 g of water, and 25 g of sodium hydroxide was dissolved in 200 g of water to prepare solutions. The three solutions were then mixed and heated to 70 °C. Sodium hydroxide solution was slowly added dropwise. After this process, the mixture was stirred at a constant temperature for 16 h, allowed to stand at room temperature for 10 h, filtered, and washed with distilled water until Cl was undetectable. - The ions were transferred to an oven and dried at 80°C for 20 hours, and then calcined at 800°C for 3 hours to obtain catalyst A.

[0037] Example 2

[0038] 137.4 g of cerium sulfate tetrahydrate was dissolved in 600 g of water, 5.1 g of calcium nitrate tetrahydrate was dissolved in 80 g of water, and 0.8 g of ruthenium trichloride hydrate (Ru content 38.7%) was dissolved in 50 g of water. 60 g of ammonia solution (concentration 28%) was diluted with 150 g of water to prepare solutions. The three solutions were then mixed and heated to 80 °C. Ammonia solution was slowly added dropwise. After this process, the mixture was stirred at a constant temperature for 10 hours. The mixture was then allowed to stand at room temperature for 16 hours before filtration. The solution was washed with distilled water until no Cl was detected. - The ions were transferred to an oven and dried at 90°C for 18 hours, and then calcined at 700°C for 3 hours to obtain catalyst B.

[0039] Example 3

[0040] 201.0 g of zirconium nitrate pentahydrate was dissolved in 600 g of water, 2.8 g of ammonium metavanadate was dissolved in 200 g of water, 0.6 g of ruthenium nitrate (Ru content 31.3%) was dissolved in 120 g of water, and 30 g of potassium hydroxide was dissolved in 130 g of water to prepare solutions. The first three solutions were then mixed and heated to 60 °C. Potassium hydroxide aqueous solution was slowly added dropwise. After completion, the mixture was stirred at a constant temperature for 3 h. After standing at room temperature for 20 h, the mixture was filtered, washed with distilled water, transferred to an oven and dried at 60 °C for 24 h, and then calcined at 400 °C for 6 h to obtain catalyst C.

[0041] Example 4

[0042] Dissolve 115.1 g of zirconium oxynitrate hydrate in 500 g of water, 0.2 g of sodium metavanadate in 50 g of water, 2.8 g of hexaammonium trichloride ruthenium hydroxide (98% purity) in 150 g of water, and 130 g of urea in 310 g of water to prepare solutions. Then, mix the first three solutions and heat to 96°C. Slowly add the urea solution dropwise. After completion, continue stirring at a constant temperature for 18 hours. Let stand at room temperature for 15 hours, then filter and wash with distilled water until Cl is undetectable. - The ions were transferred to an oven and dried at 120°C for 8 hours, and then calcined at 300°C for 8 hours to obtain catalyst D.

[0043] Example 5

[0044] Dissolve 80.6 g of zirconium oxychloride hydrate in 500 g of water, 3.8 g of magnesium chloride in 80 g of water, 6.0 g of ruthenium nitrate (Ru content 31.3%) in 160 g of water, and 60 g of ammonia solution (concentration 28%) in 150 g of water to prepare solutions. Then, mix the first three solutions and heat to 85 °C. Slowly add the ammonia solution dropwise. After completion, continue stirring at a constant temperature for 18 hours. Let stand at room temperature for 15 hours, then filter and wash with distilled water until Cl is undetectable. - The ions were transferred to an oven and dried at 120°C for 8 hours, and then calcined at 300°C for 8 hours to obtain catalyst E.

[0045] Example 6

[0046] Solutions were prepared by dissolving 97.6 g of titanium sulfate hydrate in 600 g of water, 10.7 g of calcium chloride in 160 g of water, 4.0 g of ruthenium nitrate (Ru content 31.3%) in 120 g of water, and 46 g of potassium carbonate in 200 g of water. The three solutions were then mixed and heated to 40°C. Potassium carbonate solution was slowly added dropwise. After this process, the mixture was stirred at a constant temperature for 12 hours. The mixture was then allowed to stand at room temperature for 12 hours before filtration. The solution was washed with distilled water until Cl was undetectable. - The ions were transferred to an oven and dried at 100°C for 12 hours, and then calcined at 600°C for 4 hours to obtain catalyst F.

[0047] Example 7

[0048] Solutions were prepared by dissolving 99.8 g of titanium sulfate hydrate in 600 g of water, 5.5 g of potassium metavanadate in 130 g of water, 1.7 g of hexaammonium trichloride ruthenium hydroxide (98% purity) in 120 g of water, and 52 g of sodium carbonate in 200 g of water. The three solutions were then mixed and heated to 50°C. Sodium carbonate solution was slowly added dropwise. The mixture was stirred at this constant temperature for 16 hours, allowed to stand at room temperature for 18 hours, filtered, and washed with distilled water until Cl was undetectable. - The ions were transferred to an oven and dried at 110°C for 12 hours, and then calcined at 500°C for 5 hours to obtain catalyst G.

[0049] Example 8

[0050] Solutions were prepared by dissolving 201.6 g of zirconium nitrate pentahydrate in 600 g of water, 1.4 g of ammonium metavanadate in 130 g of water, 2.6 g of ruthenium trichloride hydrate (Ru content 38.7%) in 100 g of water, and 25 g of sodium hydroxide in 200 g of water. The three solutions were then mixed and heated to 75 °C. Sodium hydroxide solution was slowly added dropwise. After this process, the mixture was stirred at a constant temperature for 10 hours, allowed to stand at room temperature for 20 hours, filtered, and washed with distilled water until Cl was undetectable. - The ions were transferred to an oven and dried at 100°C for 10 hours, and then calcined at 400°C for 6 hours to obtain catalyst H.

[0051] Example 9

[0052] 142.4 g of cerium nitrate hexahydrate was dissolved in 600 g of water, 7.6 g of calcium nitrate tetrahydrate was dissolved in 120 g of water, 5.2 g of ruthenium trichloride hydrate (Ru content 38.7%) was dissolved in 130 g of water, and 30 g of potassium hydroxide was dissolved in 60 g of water to prepare solutions. The first three solutions were then mixed and heated to 65 °C. Potassium hydroxide solution was slowly added dropwise. After this process, the mixture was stirred at a constant temperature for 8 hours. The mixture was then allowed to stand at room temperature for 15 hours before filtration. The solution was washed with distilled water until no Cl was detected. - The ions were transferred to an oven and dried at 90°C for 14 hours, and then calcined at 500°C for 5 hours to obtain catalyst I.

[0053] Example 10

[0054] 133.3g of cerium sulfate tetrahydrate was dissolved in 600g of water, 2.4g of calcium chloride in 60g of water, 2.3g of hexaammonium trichloride ruthenium chloride (98% purity) in 180g of water, and 46g of potassium carbonate in 200g of water were diluted to prepare solutions. The three solutions were then mixed and heated to 75°C. Potassium carbonate solution was slowly added dropwise. After this process, the mixture was stirred at a constant temperature for 9 hours, allowed to stand at room temperature for 17 hours, filtered, and washed with distilled water until Cl was undetectable. - The ions were transferred to an oven and dried at 110°C for 12 hours, and then calcined at 600°C for 4 hours to obtain catalyst J.

[0055] Example 11

[0056] 114.9 g of zirconium oxynitrate hydrate was dissolved in 600 g of water, 2.8 g of potassium metavanadate was dissolved in 130 g of water, 4.0 g of ruthenium nitrate (Ru content 31.3%) was dissolved in 120 g of water, and 130 g of urea was dissolved in 310 g of water to prepare solutions. The first three solutions were then mixed and heated to 86 °C. Urea solution was slowly added dropwise. After completion, the mixture was stirred at a constant temperature for 16 h. After standing at room temperature for 20 h, the mixture was filtered, washed with distilled water, transferred to an oven and dried at 90 °C for 15 h, and then calcined at 400 °C for 6 h to obtain catalyst K.

[0057] Example 12

[0058] Dissolve 84.5g of zirconium oxychloride hydrate in 500g of water, 1.9g of magnesium chloride in 80g of water, 0.9g of ruthenium trichloride hydrate (Ru content 38.7%) in 100g of water, and 46g of potassium carbonate in 200g of water to prepare solutions. Then, mix the first three solutions and heat to 75℃. Slowly add the potassium carbonate aqueous solution dropwise. After completion, continue stirring at a constant temperature for 18 hours. Let stand at room temperature for 15 hours, then filter and wash with distilled water until Cl is undetectable. - The ions were transferred to an oven and dried at 120°C for 8 hours, and then calcined at 400°C for 6 hours to obtain catalyst L.

[0059] Example 13

[0060] Dissolve 167.9 g of zirconium sulfate tetrahydrate in 600 g of water, 9.4 g of magnesium nitrate hexahydrate in 140 g of water, and 0.9 g of hexaammonium trichloride ruthenium hydroxide (98% purity) in 120 g of water. Dilute 60 g of ammonia solution (28% concentration) in 110 g of water to prepare solutions. Then, mix the first three solutions and heat to 60 °C. Slowly add the ammonia solution dropwise. After completion, continue stirring at a constant temperature for 18 h. Let stand at room temperature for 22 h, then filter and wash with distilled water until Cl is undetectable. - The ions were transferred to an oven and dried at 120°C for 10 hours, and then calcined at 600°C for 4 hours to obtain catalyst M.

[0061] Compare with Example 1

[0062] According to Example 1 of patent CN 115463657 A, a V-ZrO2 composite support was synthesized by hydrothermal method, and then a Ru / V-ZrO2 catalyst N was prepared by post-impregnation method.

[0063] Compare with Example 2

[0064] According to Example 2 of patent CN 116899549 A, ZrO2 was synthesized using a hydrothermal method, and then RuV / ZrO2 catalyst O was prepared using a co-impregnation method.

[0065] Compare with Example 3

[0066] The RuV / ZrO2 catalyst P was prepared using a co-impregnation method with commercial ZrO2.

[0067] Compare with Example 4

[0068] The RuMg / TiO2 catalyst Q was prepared using commercial TiO2 via a co-impregnation method.

[0069] Compare with Example 5

[0070] The RuCa / CeO2 catalyst R was prepared using commercial CeO2 via a co-impregnation method.

[0071] [Multi-branched isononyl alcohol oxidation reaction]

[0072] I. Evaluation Results of Stirred Tank Reactor

[0073] Using the catalysts of Examples 1-13 and Comparative Examples 1-5, and with different reduction pretreatment and oxidation reaction conditions, the oxidation reaction of multi-branched isononol was carried out in a batch reactor. The specific operation steps were as follows: 40g of the reduced pretreated catalyst and 200g of the raw material composed of multi-branched isononol and isooctane solvent (8:2 (ml / ml)) were added to a 500ml batch reactor. After adjusting the back pressure valve to 5MPa, the air flow rate was maintained at 1000mL / min throughout the reaction until the reaction was completed. The liquid phase separated after the reaction was analyzed by GC (experimental parameters and reaction results are shown in Table 1).

[0074] Table 1: Evaluation results of various catalysts in a batch reactor

[0075]

[0076] The reaction data show that the catalyst prepared by the co-precipitation method exhibits moderate reactivity and relatively high selectivity for oxidation products. Pre-reduction treatment of the catalyst before use is crucial for enhancing its reactivity. Comparative Examples 1 and 2 (catalysts N and O) were prepared by impregnation, where the anion Cl... - The catalyst was not completely removed, and the strong acid catalyst led to a high degree of cracking of the feedstock, resulting in severe corrosion of the reactor and pipelines. In Control Examples 3, 4, and 5, the post-reaction materials were darker in color, indicating severe cracking of the feedstock. ICP-MS analysis showed significant loss of metallic Ru, indicating poor catalyst stability.

[0077] To verify the stability of catalyst H prepared by the coprecipitation method, the reactants were subjected to solid-liquid separation, and the solid catalyst was returned to the reactor for repeated reactions under the same conditions as the first reaction. The results of 17 consecutive reactions are shown in the figure. Figure 1 As can be seen from the figure, the catalyst prepared by this invention has stable reaction performance.

[0078] II. Evaluation Results of Fixed-Bed Reactors

[0079] Catalysts A to M were shaped into 40-60 mesh particles and loaded into a fixed-bed reactor (pre-reduction conditions were the same as in Table 1). Air was introduced and the reaction pressure was set to 1-6 MPa. A mixture of multi-branched isononol and solvent was introduced into the reactor using a high-pressure feed pump. The reaction temperature was set to 90-150°C and the liquid hourly space velocity was set to 0.1-2.0 h⁻¹. -1 The gas space velocity is 100~5000h -1 Liquid products were periodically discharged from the outlet for GC analysis (results are shown in Table 2).

[0080] Table 2: Evaluation results of different catalysts in fixed-bed reactors

[0081]

[0082] As shown in Table 2, compared to a batch reactor, the material has more thorough contact with the catalyst with the aid of airflow. Furthermore, the residence time of the material in the catalyst bed is shortened. Therefore, the reaction activity and the selectivity of the multi-branched acid products are significantly higher than those evaluated in a batch reactor, indicating that a fixed-bed reactor is more suitable for this reaction process. Based on the degree of exothermic reaction and GC analysis results, the activity of Control Examples 1-5 decreased significantly during the reaction process.

[0083] To verify the stability of catalyst H, a long-term operation was conducted in a fixed-bed reactor. A mixture of branched isononol and isooctane at a ratio (ml / ml) of 8:2 was maintained, and the reaction was carried out at a temperature of 135℃, a pressure of 5 MPa, and a liquid hourly space velocity of 0.4 h⁻¹. -1 The gas space velocity is 400 h⁻¹ -1Under these conditions, a continuous experiment lasting up to 500 hours was conducted, and both the reaction activity and product selectivity were maintained, further demonstrating the good stability of the catalyst. Figure 2 A comparison of the XRD patterns of the catalyst before the reaction, after repeated batch reaction, and after long-term operation in a fixed bed showed that only the diffraction peaks of the ZrO2 support were observed, with no peaks of ruthenium species. This indicates that the ruthenium species remained highly dispersed in the catalyst throughout the reaction and did not undergo sintering. This also confirms the catalyst's stable performance and strong resistance to sintering.

[0084] It should be understood that the above embodiments are merely illustrative of the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. Any technical modifications made to the technical solution based on the present invention without departing from the spirit and scope of the claims should be covered within the scope of protection of the present invention.

Claims

1. A sintering-resistant ruthenium-based catalyst, characterized in that: The catalyst consists of ruthenium as the main active component, a porous metal oxide support, and an auxiliary agent. Its weight percentage composition is: ruthenium 0.1%–6%, auxiliary agent 0.15%–9%, ​​and the balance being the porous metal oxide support. The auxiliary agent is any one or a mixture of two or more of magnesium, calcium, and vanadium. The porous metal oxide support is any one or a mixture of two or more of cerium oxide, zirconium dioxide, and titanium dioxide. The preparation method of the catalyst is as follows: First, weigh the components according to the specified proportions. Then, mix an aqueous solution of ruthenium precursor (0.3%–5% by weight), an aqueous solution of auxiliary agent precursor (0.1%–8% by weight), and an aqueous solution of support precursor (5%–40% by weight), and heat the mixture to 40–96°C. Slowly add an aqueous solution of precipitant (0.3%–30% by weight), react for 3–18 hours, and then allow it to stand. After aging for 5-20 hours, the catalyst is obtained by vacuum filtration, washing with distilled water, drying at 60-120℃ for 8-24 hours, and then calcining at 300-900℃ for 3-8 hours. The ruthenium precursor in the aqueous solution is any one of ruthenium trichloride hydrate, ruthenium nitrate, and hexaammonium trichloride ruthenium. The auxiliary precursor in the aqueous solution is any one or a mixture of two or more of magnesium nitrate, magnesium chloride, calcium nitrate, calcium chloride, ammonium metavanadate, sodium metavanadate, and potassium metavanadate. The carrier precursor in the aqueous solution is any one or a mixture of two or more of cerium nitrate, cerium sulfate, zirconium nitrate, zirconium sulfate, zirconium oxynitrate, zirconium oxychloride, and titanium sulfate. The precipitant in the aqueous solution is any one or a mixture of two or more of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, urea, and ammonia.

2. The sintering-resistant ruthenium-based catalyst as described in claim 1, characterized in that: The catalyst is post-processed into granular, rod-shaped, spherical, strip-shaped, or flake-shaped forms by spray drying or extrusion.

3. The application of the sintering-resistant ruthenium-based catalyst as described in claim 1, characterized in that: In the presence of the ruthenium-based catalyst, the oxidation reaction of multi-branched isononanol is carried out in a high-pressure autoclave reactor or a fixed-bed reactor to produce multi-branched isononanoic acid; a gas mass flow meter and a back pressure valve are used at the front and rear ends of the high-pressure autoclave reactor, respectively.

4. The application of the sintering-resistant ruthenium-based catalyst as described in claim 3, characterized in that: The specific process of the oxidation reaction of multi-branched isononanol using a high-pressure autoclave reactor is as follows: First, the ruthenium-based catalyst is reduced and pretreated at 50-400℃ for 0.5-3 hours under a mixed atmosphere of 1%-5% hydrogen and 95%-99% nitrogen at atmospheric pressure; then, the mixed solution of ruthenium-based catalyst, multi-branched isononanol, and reaction solvent is reacted in an oxidizing atmosphere at 90-150℃ and 1-6MPa for 2-10 hours to obtain the multi-branched isononanoic acid product.

5. The application of the sintering-resistant ruthenium-based catalyst as described in claim 3, characterized in that: The specific process of the multi-branched isononanol oxidation reaction using a fixed-bed reactor is as follows: First, the ruthenium-based catalyst is reduced and pretreated for 0.5 to 3 hours at 50 to 400°C under a mixed atmosphere of 1% to 5% hydrogen and 95% to 99% nitrogen at atmospheric pressure; then, in an oxidizing atmosphere, a mixed solution of multi-branched isononanol and a reaction solvent is continuously fed into the reactor containing the ruthenium-based catalyst, and the reaction is carried out at a pressure of 1 to 6 MPa, a temperature of 90 to 150°C, and a liquid hourly space velocity of 0.1 to 2 h⁻¹. -1 The gas space velocity is 100~5000 h⁻¹ -1 Under certain conditions, a continuous reaction was carried out to obtain a multi-branched isononanoic acid product.

6. The application of the sintering-resistant ruthenium-based catalyst as described in claim 4 or 5, characterized in that: The reaction solvent is any one of cyclohexane, isooctane, and 1-octane, and its weight percentage concentration in the mixed solution is 0-25%.

7. The application of the sintering-resistant ruthenium-based catalyst as described in claim 4 or 5, characterized in that: The oxidizing atmosphere is one of oxygen, air, or a mixture of oxygen / nitrogen in different proportions.

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