A ruthenium-iron bimetallic supported catalyst and its application in catalytic degradation of condensed tannins

Abstract

This invention discloses a ruthenium-iron bimetallic supported catalyst and its application in the catalytic degradation of condensed tannins, belonging to the fields of catalysts and biomass resource utilization. The ruthenium-iron bimetallic supported catalyst of this invention uses mesoporous ZrO2 as a support and supports Ru and Fe bimetals as catalytically active components. The Ru-Fe bimetallic components in this catalyst exhibit a synergistic effect with the acidic sites of the ZrO2 support, which can efficiently activate and promote the directional breaking of C-C bonds in organic matter, thereby achieving deep degradation of the target substrate (condensed tannins). The ruthenium-iron bimetallic supported catalyst prepared by this invention can achieve a condensed tannin degradation rate ≥75%, with an average degree of polymerization ≤2.5 and a total hydroxyl content ≥20% of the degradation products. Compared with traditional noble metal catalysts, the ruthenium-iron bimetallic supported catalyst prepared by this invention has a significant cost advantage, improving its economic efficiency and market competitiveness.

Description

Technical Field

[0001] This invention belongs to the field of catalyst and biomass resource utilization technology, and particularly relates to a ruthenium-iron bimetallic supported catalyst and its application in the catalytic degradation of condensed tannins. Background Technology

[0002] Condensed tannins are a class of natural polyphenol polymers widely found in plants, commonly found in bark, fruits, and tea. Condensed tannins are classified into polymeric and oligomeric condensed tannins. Studies have shown that polymeric condensed tannins have large molecular weights, are difficult to permeate biological membranes, have low bioavailability, and poor activity, making them suitable only for manufacturing adhesives and other chemical products. In contrast, oligomeric condensed tannins exhibit strong biological activity, possessing free radical scavenging, antioxidant, anti-inflammatory, and tumor-inhibiting effects, and have broad application prospects in functional foods, cosmetics, and pharmaceuticals. Their economic value is more than 100 times higher than that of polymeric condensed tannins. Therefore, how to efficiently degrade polymeric condensed tannins to obtain oligomers with stronger biological activity is currently a hot research topic.

[0003] Degradation methods for polycondensed tannins include alkaline degradation, oxidative degradation, biodegradation, and hydrogenolysis with noble metal catalysts. Alkaline and oxidative degradation methods use reagents that corrode equipment and pollute the environment; oxidants can also oxidize phenolic hydroxyl groups, reducing the bioactivity of the degradation products. Biodegradation primarily targets hydrolyzed tannins, making the degradation of condensed tannins more difficult, and the uncertainty of screening degrading bacteria and the reaction process limits its application. Compared to the above methods, hydrogenolysis with noble metal catalysts offers advantages such as low corrosivity, simple operation, and strong bioactivity of the resulting oligomeric condensed tannins, making it a relatively efficient and green degradation method. However, single noble metal catalysts (such as palladium-based catalysts) suffer from poor stability, low reproducibility, low active sites, and high cost. Therefore, developing a catalyst with high activity, high selectivity, and good stability to achieve efficient degradation of condensed tannins under mild conditions is of great significance for the high-value utilization of plant resources and the development of green chemical processes. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention proposes a ruthenium-iron bimetallic supported catalyst and its application in the catalytic degradation of condensed tannins. This invention provides a low-cost, highly active bimetallic catalyst that, through optimized support structure and metal synergistic effects, achieves efficient hydrogenolysis of condensed tannins, reduces the degree of polymerization, and increases the added value of the product.

[0005] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a ruthenium-iron bimetallic supported catalyst for the catalytic degradation of condensed tannins, using mesoporous zirconium dioxide (ZrO2) as a support and supporting ruthenium (Ru) and iron (Fe) bimetals as catalytic active components; The total loading of Ru and Fe bimetals was 5-6 wt%. The molar ratio of Ru to Fe is 1:1.

[0006] The ruthenium-iron bimetallic supported catalyst prepared in this invention has a high efficiency of catalytic degradation. The Ru-Fe bimetallic component in the catalyst has a synergistic effect with the acidic sites of the support ZrO2, which can efficiently activate and promote the directional breaking of C-C bonds in organic matter, thereby achieving deep degradation of the target substrate (condensed tannins).

[0007] Preferably, the total loading of Ru and Fe bimetals is 5.4~6 wt%.

[0008] This invention also provides a method for preparing a ruthenium-iron bimetallic supported catalyst for the catalytic degradation of condensed tannins, comprising the following steps: S1. Dissolve the triblock copolymer Pluronic P123 in a mixed solution of water and hydrochloric acid (HCl), then add tetraethyl orthosilicate (TEOS) dropwise, stir the reaction, and subject the resulting white suspension to hydrothermal treatment. Filter and dry the resulting mesoporous silica composite material. Reflux the solid with nitric acid (HNO3) solution and hydrogen peroxide (H2O2), wash and dry to obtain the SBA-15-OH molecular sieve template. S2. After dissolving ZrOCl2·8H2O in dilute HCl solution, it is mixed with the SBA-15-OH molecular sieve template by a proportional impregnation method, aged, then calcined, and finally etched with sodium hydroxide (NaOH) solution to remove silicon, washed and dried to obtain ZrO2. S3. Mix Fe(NO3)3•9H2O solution and RuCl3 solution evenly as catalyst precursor solution; pour the catalyst precursor solution into ZrO2 for thorough impregnation, freeze dry, reduce with sodium borohydride (NaBH4) solution, centrifuge, wash with water, and vacuum dry to obtain the ruthenium-iron bimetallic supported catalyst for catalytic degradation of condensed tannins.

[0009] The principle of this invention is as follows: 1. Ru-Fe bimetallic synergistic activation of C / C / CO bonds enables deep degradation. Condensed tannins are complex polymers composed of flavan-3-ol units linked by C-C bonds and CO-C ether bonds. The lack of Fe in pure Ru catalysts may limit the electronic coupling of the bimetallic structure and the diversity of active sites, while pure Fe catalysts exhibit weak activation capabilities. In this invention, the introduction of Fe alters the electronic structure of Ru (forming a Ru-Fe interface), optimizing the adsorption energy of the active sites on the substrate. This electronic coupling effect enables the catalyst to precisely and directionally activate and break the extremely stable C-C and CO bonds in the condensed tannin framework, thereby significantly improving the overall degradation rate.

[0010] 2. Suppresses cascade hydrogenation and excessive cracking, effectively reducing the average degree of polymerization. In traditional noble metal catalysis, long-chain polymers are prone to uncontrolled cascade hydrogenation reactions, leading to continuous carbon chain breakage from the end to generate low-value small molecule alkanes. The Ru-Fe bimetallic component of this invention exhibits a strong synergistic effect with the acidic sites of the mesoporous ZrO2 support. The Lewis acid sites on the ZrO2 surface can effectively adsorb and polarize oxygen atoms in tannin molecules, weakening adjacent C / C / CO bonds; simultaneously, the bimetallic interface promotes the transfer of active hydrogen species to specific bond-breaking sites, accelerating the desorption of intermediate products. This process acts like a "brake" on excessive pyrolysis, successfully blocking unrestricted chain pyrolysis and keeping the products mainly within the ideal range of dimers to pentamers, significantly reducing the average degree of polymerization.

[0011] 3. Promotes selective hydrogenolysis, maximizing the retention and increasing the total hydroxyl content. The high added value of condensed tannins lies primarily in their abundant phenolic hydroxyl groups. Conventional strong acid or vigorous pyrolysis conditions easily lead to dehydration of the phenolic hydroxyl groups or condensation side reactions. In the mild catalytic system of this invention (150 °C, 4 MPa), Ru-Fe / ZrO2 exhibits excellent chemoselectivity. The bimetallic active center preferentially attacks bridging bonds connecting monomer units (such as alkylaryl ether bonds), while providing extremely high protection for the phenolic hydroxyl groups on the benzene ring. Furthermore, the activated hydrogen species in the reaction system, after cleaving the CO bond, rapidly saturate-cap the generated free radical intermediates, preventing the formation of oxidized structures such as quinones. Therefore, degradation not only does not destroy the original phenolic hydroxyl groups, but also exposes more previously encapsulated free hydroxyl groups by opening the cross-linking network, resulting in a total hydroxyl content of ≥20% in the final product, endowing it with excellent antioxidant properties.

[0012] Further, in step S1, the mass ratio of the triblock copolymer Pluronic P123 to TEOS is 4:8.5.

[0013] Furthermore, in step S1, the temperature of the stirring reaction is 38°C and the time is 24 h; The hydrothermal treatment was performed at a temperature of 110 °C for 24 h. The reflux treatment was performed at a temperature of 80 °C for 3 hours.

[0014] For example, in step S1, the concentration of hydrochloric acid is 37% (volume fraction, the same below).

[0015] For example, in step S1, the mass ratio of water to hydrochloric acid is 1:4.

[0016] For example, in step S1, the mesoporous silica composite material is filtered and then dried at 50 °C.

[0017] For example, in step S1, the concentration of HNO3 solution is 65 wt%, and the volume is 50 mL; the concentration of H2O2 is 35 wt%, and the volume is 16.6 mL.

[0018] Furthermore, in step S2, the mass ratio of the ZrOCl2·8H2O to the SBA-15-OH molecular sieve template is 4:1.

[0019] Further, in step S2, the aging process is as follows: first aging at 50 ℃ for 24 h, and then aging at 90 ℃ for 48 h; The calcination treatment is as follows: at 1 °C·min -1 The calcination rate was increased to 500 °C for 5 h.

[0020] For example, in step S2, the concentration of the dilute HCl solution is 1.07M.

[0021] For example, in step S2, the concentration of the NaOH solution is 2M, and the etching temperature for removing silicon is 70°C.

[0022] Further, in step S3, the concentration of the Fe(NO3)3•9H2O solution is 0.2 g / mL; the concentration of the RuCl3 solution is 0.2 g / mL.

[0023] For example, in step S3, the concentration of the NaBH4 solution is 25 mg / mL, and the reduction time is 30 min.

[0024] For example, in step S3, the temperature for vacuum drying is 60 °C.

[0025] An exemplary method for preparing a ruthenium-iron bimetallic supported catalyst for the catalytic degradation of condensed tannins includes the following steps: S1. Template preparation: Using triblock copolymer Pluronic P123 as the template agent and tetraethyl orthosilicate (TEOS) as the silicon source, P123 (4.00 g) was dissolved in distilled water (30.00 g) and 37% HCl (120.00 g), followed by the dropwise addition of TEOS (8.50 g, 0.05 mol). After stirring at 38 °C for 24 h, the resulting white suspension was transferred to an autoclave and then hydrothermally treated at 110 °C for 24 h. The resulting mesoporous silica composite material was filtered and further dried at 50 °C. The resulting solid was detemplated by refluxing at 80 °C for 3 h with HNO3 (65 wt%, 50 mL) and H2O2 (35 wt%, 16.6 mL), and then washed and dried to obtain the SBA-15-OH molecular sieve template. S2. Zirconium source impregnation: Dissolve 4.0 g ZrOCl2·8H2O in 4 mL of dilute HCl (1.07 M) solution, then mix with 1.00 g SBA-15-OH molecular sieve template using a proportional impregnation method. Aging is carried out at 50 ℃ for 24 h and at 90 ℃ for 48 h, followed by impregnation at 1 ℃·min. -1 The calcination rate was increased to 500 °C and calcined for 5 h; finally, silicon was removed by etching three times at 70 °C using 35 mL of NaOH solution (2 M), and the resulting product was washed and dried to obtain ZrO2 with high specific surface area. S3. Supported Metal: Fe(NO3)3•9H2O solution and RuCl3 solution were mixed evenly as the catalyst precursor solution; the catalyst precursor solution was poured into 0.1g ZrO2 for thorough impregnation, freeze-dried, then reduced with 1 mL NaBH4 solution (25mg / mL) for 30 min, centrifuged, washed with water, and vacuum dried at 60 ℃ to obtain a ruthenium-iron bimetallic supported catalyst for the catalytic degradation of condensed tannins, denoted as (RuCl3)2. x -Fe y )5 / ZrO2, where x=1 or 2, y=1 or 2.

[0026] For example, when x=1 and y=1, step S3 is as follows: Take 0.2g Fe(NO3)3•9H2O and 0.2g RuCl3 and dilute them to 1mL in a volumetric flask to obtain Fe(NO3)3•9H2O solution and RuCl3 solution respectively; take 0.064mL of Fe(NO3)3•9H2O solution and 0.033mL of RuCl3 solution respectively and mix them evenly as catalyst precursor solution; pour the catalyst precursor solution into 0.1g ZrO2 and impregnate it fully, freeze dry it, then reduce it with 1mL NaBH4 solution (25mg / mL) for 30min, centrifuge, wash with water, and vacuum dry at 60℃ to obtain ruthenium-iron bimetallic supported catalyst for catalytic degradation of condensed tannins, denoted as (Ru1-Fe1)5 / ZrO2.

[0027] For example, when x=1 and y=2, step S3 is as follows: Take 0.2g Fe(NO3)3•9H2O and 0.2g RuCl3 and dilute them to 1mL in a volumetric flask to obtain Fe(NO3)3•9H2O solution and RuCl3 solution respectively; take 0.09mL of Fe(NO3)3•9H2O solution and 0.02mL of RuCl3 solution respectively and mix them evenly as catalyst precursor solution; pour the catalyst precursor solution into 0.1g ZrO2 and impregnate it thoroughly, freeze dry it, then reduce it with 1mL NaBH4 solution (25mg / mL) for 30min, centrifuge, wash with water, and vacuum dry at 60℃ to obtain ruthenium-iron bimetallic supported catalyst, denoted as (Ru1-Fe2)5 / ZrO2.

[0028] For example, when x=2 and y=1, step S3 is as follows: Take 0.2g of Fe(NO3)3•9H2O and 0.2g of RuCl3 and dilute them to 1mL in a volumetric flask to obtain Fe(NO3)3•9H2O solution and RuCl3 solution respectively; take 0.039mL of Fe(NO3)3•9H2O solution and 0.04mL of RuCl3 solution respectively and mix them evenly as catalyst precursor solution; pour the catalyst precursor solution into 0.1g of ZrO2 and impregnate it thoroughly, freeze dry it, then reduce it with 1mL of NaBH4 solution (25mg / mL) for 30min, centrifuge, wash with water, and vacuum dry at 60℃ to obtain ruthenium-iron bimetallic supported catalyst, denoted as (Ru2-Fe1)5 / ZrO2.

[0029] For example, when only Ru metal is available, step S3 is as follows: Take 0.2 g RuCl3 and dilute it to 1 mL in a volumetric flask to obtain RuCl3 solution; take 0.64 mL of RuCl3 solution as catalyst precursor solution; pour the catalyst precursor solution into 0.1 g ZrO2 for thorough impregnation, freeze dry, then reduce with 1 mL NaBH4 solution (25 mg / mL) for 30 min, centrifuge, wash with water, and vacuum dry at 60 ℃ to obtain ruthenium-iron bimetallic supported catalyst, denoted as Ru5 / ZrO2.

[0030] The present invention also provides an application of the above-mentioned ruthenium-iron bimetallic supported catalyst in the catalytic degradation of condensed tannins.

[0031] Furthermore, the amount of the ruthenium-iron bimetallic supported catalyst added is 0.25~0.5g / 1g condensed tannin; the degradation temperature is 150 ℃, the time is 3 h, and the pressure is 4 MPa.

[0032] The ruthenium-iron bimetallic supported catalyst prepared by this invention can achieve a degradation rate of condensed tannins ≥75%, with an average degree of polymerization of degradation products ≤2.5 and a total hydroxyl content ≥20%. Compared with traditional precious metal catalysts, the ruthenium-iron bimetallic supported catalyst prepared by this invention has a significant cost advantage, enhancing its economic viability and market competitiveness.

[0033] Compared with the prior art, the present invention has the following advantages and technical effects: The ruthenium-iron bimetallic supported catalyst prepared in this invention exhibits highly efficient catalytic degradation capabilities. The Ru-Fe bimetallic component in this catalyst works synergistically with the acidic sites of the ZrO2 support, efficiently activating and promoting the directional breaking of C-C bonds in organic matter, thereby achieving deep degradation of the target substrate. Experiments show that, under 0.025 g conditions, the degradation performance of the four catalytic systems exhibits significant differences: the tannin degradation rates for Ru5 / ZrO2, (Ru1-Fe1)5 / ZrO2, (Ru2-Fe1)5 / ZrO2, and (Ru1-Fe2)5 / ZrO2 are 48.97%, 67.34%, 62.24%, and 52.04%, respectively; the average degree of polymerization of their degradation products are 4.0, 3.2, 3.7, and 4.7, respectively. Experimental data indicate that the bimetallic catalyst (Ru1-Fe1)5 / ZrO2 with a Ru-Fe molar ratio of 1:1 exhibits the best catalytic performance. Its degradation efficiency is more than 20% higher than that of single metal catalysts under the same conditions, demonstrating excellent catalytic activity.

[0034] The ruthenium-iron bimetallic catalyst prepared by this invention has a significant cost advantage. Its cost is far lower than that of catalysts using the traditional noble metal palladium (Pd) as the active component. The catalyst of this invention uses ruthenium (Ru) as the main active component and innovatively introduces the non-noble metal iron (Fe) to form a bimetallic structure. While ensuring activity, it significantly reduces the overall amount of noble metal used, thereby greatly compressing the catalyst's production cost and improving its economic efficiency and market competitiveness.

[0035] This invention enables the high-value utilization of condensed tannin degradation products. After degradation by a ruthenium-iron bimetallic supported catalytic system, the degradation products are polymers ranging from dimers to pentamers, with dimer peaks predominating. These polymers exhibit excellent antioxidant properties, and their DPPH free radical scavenging ability is superior to that of the commonly used antioxidant vitamin C, greatly enhancing the added value and application potential of the degradation products. Attached Figure Description

[0036] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 The images show the scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) spectra of the support (ZrO2) obtained in Example 1, the ruthenium-iron bimetallic supported catalysts obtained in Examples 1 and 2, and the Ru5 / ZrO2 obtained in Comparative Example 3. (a) is the SEM image of ZrO2, (b) is the SEM image of (Ru1-Fe1)5 / ZrO2, (c) is the SEM image of (Ru2-Fe1)5 / ZrO2, (d) is the SEM image of (Ru1-Fe2)5 / ZrO2, and (e) is the SEM image of Ru5 / ZrO2. f~m are the SES spectra of Zr, Ru, and Fe elements in (Ru1-Fe1)5 / ZrO2, (Ru2-Fe1)5 / ZrO2, (Ru1-Fe2)5 / ZrO2, and Ru5 / ZrO2, respectively. Figure 2 The XRD patterns are of ZrO2 obtained in Example 1, Ru5 / ZrO2 obtained in Comparative Example 3, and ruthenium-iron bimetallic supported catalysts obtained in Example 1 and Comparative Examples 1-2. Figure 3 The images are TEM images of the ZrO2 and (Ru1-Fe1)5 / ZrO2 carriers obtained in Example 1 at different magnifications of 800,000×. (a) is ZrO2, 200,000×; (b) is ZrO2, 800,000×; (c) is (Ru1-Fe1)5 / ZrO2, 200,000×; (d) is (Ru1-Fe1)5 / ZrO2, 800,000×. Figure 4XPS spectra of the ruthenium-iron bimetallic supported catalyst ((Ru1-Fe1)5 / ZrO2) obtained in Example 1: (a) is the full spectrum, (b) is the fine spectrum of Fe 2p, and (c) is the fine spectrum of Ru 3p. Figure 5 This is a comparative study of the DPPH· free radical scavenging activities of polymeric proanthocyanidins (PPC), oligomeric proanthocyanidins (LOPC), and ascorbic acid (VC). Detailed Implementation

[0037] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0038] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0039] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0040] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0041] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0042] Embodiments of the present invention provide a ruthenium-iron bimetallic supported catalyst for the catalytic degradation of condensed tannins, using mesoporous ZrO2 as a support and loading Ru and Fe bimetals as catalytic active components; The total loading of Ru and Fe bimetals was 5-6 wt%. The molar ratio of Ru to Fe is 1:1.

[0043] In a preferred embodiment of the present invention, the total loading of Ru and Fe bimetals is 5.4 to 6 wt%.

[0044] Embodiments of the present invention also provide a method for preparing a ruthenium-iron bimetallic supported catalyst for the catalytic degradation of condensed tannins, comprising the following steps: S1. Dissolve the triblock copolymer Pluronic P123 in a mixed solution of water and HCl, then add TEOS dropwise, stir and react, subject the white suspension after reaction to hydrothermal treatment, filter and dry the resulting mesoporous silica composite material, and use HNO3 solution and H2O2 to reflux and remove the template, wash and dry to obtain SBA-15-OH molecular sieve template. S2. After dissolving ZrOCl2·8H2O in dilute HCl solution, it is mixed with SBA-15-OH molecular sieve template by impregnation in equal proportion, aged, then calcined, and finally etched with NaOH solution to remove silicon, washed and dried to obtain ZrO2. S3. Mix Fe(NO3)3•9H2O solution and RuCl3 solution evenly as catalyst precursor solution; pour the catalyst precursor solution into ZrO2 for thorough impregnation, freeze dry, then reduce with NaBH4 solution, centrifuge, wash with water, and vacuum dry to obtain ruthenium-iron bimetallic supported catalyst for catalytic degradation of condensed tannins.

[0045] In a preferred embodiment of the present invention, in step S1, the mass ratio of the triblock copolymer Pluronic P123 to TEOS is 4:8.5.

[0046] In a preferred embodiment of the present invention, in step S1, the temperature of the stirring reaction is 38°C and the time is 24 h; The hydrothermal treatment was carried out at a temperature of 110 ℃ for 24 h. The reflux treatment was carried out at a temperature of 80 °C for 3 h.

[0047] For example, in step S1, the concentration of hydrochloric acid is 37% (volume fraction, the same below).

[0048] For example, in step S1, the mass ratio of water to hydrochloric acid is 1:4.

[0049] For example, in step S1, the mesoporous silica composite material is filtered and then dried at 50 °C.

[0050] For example, in step S1, the concentration of HNO3 solution is 65 wt%, and the volume is 50 mL; the concentration of H2O2 is 35 wt%, and the volume is 16.6 mL.

[0051] In a preferred embodiment of the present invention, in step S2, the mass ratio of ZrOCl2·8H2O to SBA-15-OH molecular sieve template is 4:1.

[0052] In a preferred embodiment of the present invention, in step S2, the aging process is as follows: first aging at 50 °C for 24 h, and then aging at 90 °C for 48 h; The calcination process was carried out at 1 °C / min. -1 The calcination rate was increased to 500 °C for 5 h.

[0053] For example, in step S2, the concentration of the dilute HCl solution is 1.07M.

[0054] For example, in step S2, the concentration of the NaOH solution is 2M, and the etching temperature for removing silicon is 70°C.

[0055] In a preferred embodiment of the present invention, in step S3, the concentration of the Fe(NO3)3•9H2O solution is 0.2 g / mL; the concentration of the RuCl3 solution is 0.2 g / mL.

[0056] For example, in step S3, the concentration of the NaBH4 solution is 25 mg / mL, and the reduction time is 30 min.

[0057] For example, in step S3, the temperature for vacuum drying is 60 °C.

[0058] An exemplary method for preparing a ruthenium-iron bimetallic supported catalyst for the catalytic degradation of condensed tannins includes the following steps: S1. Template preparation: Using triblock copolymer Pluronic P123 as the template agent and TEOS as the silicon source, P123 (4.00 g) was dissolved in distilled water (30.00 g) and 37% HCl (120.00 g), followed by the dropwise addition of TEOS (8.50 g, 0.05 mol). After stirring and reacting at 38 °C for 24 h, the resulting white suspension was transferred to an autoclave and then hydrothermally treated at 110 °C for 24 h. The resulting mesoporous silica composite material was filtered and further dried at 50 °C. The resulting solid was detemplated by refluxing at 80 °C for 3 h with HNO3 (65 wt%, 50 mL) and H2O2 (35 wt%, 16.6 mL), and then washed and dried to obtain the SBA-15-OH molecular sieve template. S2. Zirconium source impregnation: Dissolve 4.0 g ZrOCl2·8H2O in 4 mL of dilute HCl (1.07 M) solution, then mix with 1.00 g SBA-15-OH molecular sieve template using a proportional impregnation method. Aging is carried out at 50 ℃ for 24 h and at 90 ℃ for 48 h, followed by impregnation at 1 ℃·min. -1 The temperature was raised to 500 °C and calcined for 5 h. Finally, silicon was removed by etching three times at 70 °C using 35 mL of NaOH solution (2 M). After washing and drying, ZrO2 with high specific surface area was obtained. S3. Supported Metal: Fe(NO3)3•9H2O solution and RuCl3 solution were mixed evenly as the catalyst precursor solution; the catalyst precursor solution was poured into 0.1g ZrO2 for thorough impregnation, freeze-dried, then reduced with 1 mL NaBH4 solution (25mg / mL) for 30 min, centrifuged, washed with water, and vacuum dried at 60 ℃ to obtain a ruthenium-iron bimetallic supported catalyst for the catalytic degradation of condensed tannins, denoted as (RuCl3)2. x -Fe y )5 / ZrO2, where x=1 or 2, y=1 or 2.

[0059] For example, when x=1, y=1 (i.e., n(Ru):n(Fe)=1:1), step S3 is as follows: Take 0.2g Fe(NO3)3•9H2O and 0.2g RuCl3 and dilute them to 1mL in a volumetric flask to obtain Fe(NO3)3•9H2O solution and RuCl3 solution respectively; take 0.054mL of Fe(NO3)3•9H2O solution and 0.033mL of RuCl3 solution respectively and mix them evenly as catalyst precursor solution; pour the catalyst precursor solution into 0.1g ZrO2 and impregnate it thoroughly, freeze dry it, then reduce it with 1mL NaBH4 solution (25mg / mL) for 30min, centrifuge, wash with water, and vacuum dry at 60℃ to obtain ruthenium-iron bimetallic supported catalyst for catalytic degradation of condensed tannins, denoted as (Ru1-Fe1)5 / ZrO2.

[0060] For example, when x=1 and y=2 (i.e., n(Ru):n(Fe)=1:2), step S3 is as follows: Take 0.2g Fe(NO3)3•9H2O and 0.2g RuCl3 and dilute them to 1mL in a volumetric flask to obtain Fe(NO3)3•9H2O solution and RuCl3 solution respectively; take 0.09mL of Fe(NO3)3•9H2O solution and 0.02mL of RuCl3 solution respectively and mix them evenly as catalyst precursor solution; pour the catalyst precursor solution into 0.1g ZrO2 and impregnate it thoroughly, freeze dry it, then reduce it with 1mL NaBH4 solution (25mg / mL) for 30min, centrifuge, wash with water, and vacuum dry at 60℃ to obtain ruthenium-iron bimetallic supported catalyst, denoted as (Ru1-Fe2)5 / ZrO2.

[0061] For example, when x=2 and y=1 (i.e., n(Ru):n(Fe)=2:1), step S3 is as follows: Take 0.2g Fe(NO3)3•9H2O and 0.2g RuCl3 and dilute them to 1mL in a volumetric flask to obtain Fe(NO3)3•9H2O solution and RuCl3 solution respectively; take 0.039mL of Fe(NO3)3•9H2O solution and 0.04mL of RuCl3 solution and mix them evenly as catalyst precursor solution; pour the catalyst precursor solution into 0.1g ZrO2 and impregnate it thoroughly, freeze dry it, then reduce it with 1mL NaBH4 solution (25mg / mL) for 30min, centrifuge, wash with water, and vacuum dry at 60℃ to obtain ruthenium-iron bimetallic supported catalyst, denoted as (Ru2-Fe1)5 / ZrO2.

[0062] For example, when only Ru metal is available, step S3 is as follows: Take 0.2 g RuCl3 and dilute it to 1 mL in a volumetric flask to obtain RuCl3 solution; take 0.64 mL of RuCl3 solution as catalyst precursor solution; pour the catalyst precursor solution into 0.1 g ZrO2 for thorough impregnation, freeze dry, then reduce with 1 mL NaBH4 solution (25 mg / mL) for 30 min, centrifuge, wash with water, and vacuum dry at 60 ℃ to obtain ruthenium-iron bimetallic supported catalyst, denoted as Ru5 / ZrO2.

[0063] The embodiments of the present invention also provide an application of the above-mentioned ruthenium-iron bimetallic supported catalyst in the catalytic degradation of condensed tannins, which is particularly suitable for the efficient degradation of highly polymerized condensed tannins in larch bark.

[0064] In a preferred embodiment of the present invention, the amount of ruthenium-iron bimetallic supported catalyst added is 0.25~0.5g / 1g condensed tannin; the degradation temperature is 150 ℃, the time is 3 h, and the pressure is 4 MPa.

[0065] This invention enables the high-value utilization of condensed tannin degradation products. After degradation by a ruthenium-iron bimetallic supported catalytic system, the degradation products are polymers ranging from dimers to pentamers, with dimer peaks predominating. These polymers exhibit excellent antioxidant properties, and their DPPH free radical scavenging ability is superior to that of the commonly used antioxidant vitamin C, greatly enhancing the added value and application potential of the degradation products.

[0066] In the following embodiments of the present invention, the preparation method of polyproanthocyanidins (PPC) is as follows: 80-100 mesh larch bark powder is added to 60% (volume percentage, the same below) ethanol at a material-to-liquid ratio of 1g:12mL, and ultrasonically extracted at 320 W for 20 min. The extract is filtered and concentrated, allowed to stand for 12 h, filtered again, and the filtrate is loaded into three extraction tubes connected in series with crushed magnetic rings. The filtrate is extracted countercurrently with ethyl acetate. The aqueous phase of the raffinate is passed into an HP2MGL resin column at a flow rate of 3 BV / h. After saturation adsorption, the column is eluted sequentially with a gradient of 10%, 30%, 50%, and 70% ethanol. The 70% ethanol eluent is freeze-dried to obtain polyproanthocyanidins (PPC).

[0067] Unless otherwise specified, the room temperature in this invention is 25±2℃.

[0068] All raw materials used in the embodiments of this invention were purchased commercially. For example, the triblock copolymer Pluronic P123 (analytical grade) was purchased from Anaiji Chemical; tetraethyl orthosilicate (analytical grade) was purchased from Anaiji Chemical; and larch bark condensed tannin (degree of polymerization 9.8) was purchased from Chengdu Letianmei Technology Co., Ltd.

[0069] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0070] The technical solution of the present invention will be further illustrated by the following embodiments.

[0071] Example 1 A method for preparing a ruthenium-iron bimetallic supported catalyst, comprising the following steps: Template preparation: Using triblock copolymer Pluronic P123 as the template agent and tetraethyl orthosilicate (TEOS) as the silicon source, Pluronic P123 (4.00 g) was dissolved in a mixed solution of distilled water (30.00 g) and 37% HCl (120.00 g), followed by the dropwise addition of TEOS (8.50 g, 0.05 mol). After stirring at 38 °C for 24 h, the resulting white suspension was transferred to an autoclave and then hydrothermally treated at 110 °C for 24 h. The resulting mesoporous silica composite material was filtered and further dried at 50 °C. The resulting solid was detemplated by refluxing at 80 °C for 3 h with HNO3 (65 wt%, 50 mL) and H2O2 (35 wt%, 16.6 mL), and then washed and dried to obtain the SBA-15-OH molecular sieve template.

[0072] Zirconium source impregnation: 4.0 g ZrOCl2·8H2O was dissolved in 4 mL of dilute HCl (1.07 M) solution, and then mixed with 1.00 g SBA-15-OH molecular sieve template using a proportional impregnation method. The mixture was aged at 50 ℃ for 24 h and at 90 ℃ for 48 h, and then further aged at 1 ℃·min. -1 The etching rate was increased to 500 °C and calcined for 5 h; finally, silicon was removed by etching three times at 70 °C using 35 mL of NaOH solution (2 M), followed by washing and drying to obtain ZrO2 with a high specific surface area (BET specific surface area of ​​208 m²). 2 / g), which has a nanotube structure.

[0073] Metal loading: 0.2 g Fe(NO3)3•9H2O and 0.2 g RuCl3 were respectively diluted to 1 mL in volumetric flasks to obtain Fe(NO3)3•9H2O solution and RuCl3 solution; 0.064 mL of Fe(NO3)3•9H2O solution and 0.033 mL of RuCl3 solution were respectively mixed evenly as catalyst precursor solution; the catalyst precursor solution was poured into 0.1 g ZrO2 for thorough impregnation, freeze-dried, and then reduced with 1 mL NaBH4 solution (25 mg / mL) for 30 min. After centrifugation, washing with water, and vacuum drying at 60 ℃, a ruthenium-iron bimetallic supported catalyst was obtained, denoted as (Ru1-Fe1)5 / ZrO2, with a total loading of 5 wt% of Ru and Fe bimetals.

[0074] The ruthenium-iron bimetallic supported catalyst obtained in this embodiment was used to catalyze the degradation of condensed tannins. The specific steps were as follows: 0.1 g of larch bark condensed tannins (degree of polymerization 9.8) was dissolved in 10 mL of distilled water. Then, the resulting solution was added to a high-pressure reactor with 0.05 g of the (Ru1-Fe1)5 / ZrO2 catalyst prepared in this embodiment. H2 was added to 4 MPa, and the reaction was carried out at 150 °C for 3 h. The product was separated by centrifugation, and the average degree of polymerization was measured to be 2.33, the degradation rate was 76.22%, and the total hydroxyl content increased from 11.85% to 20.05%.

[0075] Comparative Example 1 A method for preparing a ruthenium-iron bimetallic supported catalyst, comprising the following steps: Template preparation: Same as in Example 1.

[0076] Zirconium source impregnation: Same as in Example 1.

[0077] Metal loading: 0.2 g Fe(NO3)3•9H2O and 0.2 g RuCl3 were respectively diluted to 1 mL in volumetric flasks to obtain Fe(NO3)3•9H2O solution and RuCl3 solution; 0.09 mL of Fe(NO3)3•9H2O solution and 0.02 mL of RuCl3 solution were respectively mixed evenly as catalyst precursor solution; the catalyst precursor solution was poured into 0.1 g ZrO2 for thorough impregnation, freeze-dried, and then reduced with 1 mL NaBH4 solution (25 mg / mL) for 30 min. After centrifugation, washing with water, and vacuum drying at 60 ℃, a ruthenium-iron bimetallic supported catalyst was obtained, denoted as (Ru1-Fe2)5 / ZrO2, with a total loading of 5 wt% of Ru and Fe bimetals.

[0078] The ruthenium-iron bimetallic supported catalyst obtained in this comparative example was used to catalyze the degradation of condensed tannins. The specific steps were as follows: 0.025 g of larch bark condensed tannins (degree of polymerization 9.8) was dissolved in 10 mL of distilled water. Then, the resulting solution and 0.025 g of the (Ru1-Fe2)5 / ZrO2 catalyst prepared in this comparative example were added to a high-pressure reactor, H2 was added to 4 MPa, and the reaction was carried out at 150 °C for 3 h. The product was separated by centrifugation, and the average degree of polymerization was measured to be 4.7, and the degradation rate was 52.04%.

[0079] Comparative Example 2 A method for preparing a ruthenium-iron bimetallic supported catalyst, comprising the following steps: Template preparation: Same as in Example 1.

[0080] Zirconium source impregnation: Same as in Example 1.

[0081] Metal loading: 0.2 g Fe(NO3)3•9H2O and 0.2 g RuCl3 were respectively diluted to 1 mL in volumetric flasks to obtain Fe(NO3)3•9H2O solution and RuCl3 solution; 0.039 mL of Fe(NO3)3•9H2O solution and 0.04 mL of RuCl3 solution were respectively mixed evenly as catalyst precursor solution; the catalyst precursor solution was poured into 0.1 g ZrO2 for thorough impregnation, freeze-dried, and then reduced with 1 mL NaBH4 solution (25 mg / mL) for 30 min. After centrifugation, washing with water, and vacuum drying at 60 ℃, a ruthenium-iron bimetallic supported catalyst was obtained, denoted as (Ru2-Fe1)5 / ZrO2, with a total loading of 5 wt% of Ru and Fe bimetals.

[0082] The ruthenium-iron bimetallic supported catalyst obtained in this comparative example was used to catalyze the degradation of condensed tannins. The specific steps were as follows: 0.025 g of larch bark condensed tannins (degree of polymerization 9.8) was dissolved in 10 mL of distilled water. Then, the resulting solution and 0.025 g of the (Ru2-Fe1)5 / ZrO2 catalyst prepared in this comparative example were added to a high-pressure reactor, H2 was added to 4 MPa, and the reaction was carried out at 150 °C for 3 h. The product was separated by centrifugation, and the average degree of polymerization was measured to be 3.7, with a degradation rate of 62.24%.

[0083] The ability of degradation products (LOPC) to scavenge DPPH free radicals was determined as follows: Based on the DPPH free radical scavenging rate evaluation system, the experiment was designed as follows: A precise 0.04 mg / mL DPPH / ethanol solution system was prepared and stored in the dark at 0–4°C for later use. 0.25 mL of gradient concentration tannin sample solution and 4.75 mL of DPPH working solution were added to a stoppered brown colorimetric tube, vortexed to mix, and reacted in the dark for 30 min. A background subtraction system was established using 70% ethanol solution, and the absorbance change was detected at the characteristic wavelength of 517 nm using a UV spectrophotometer. The DPPH free radical scavenging rate was calculated using the following formula. Following this method, the DPPH free radical scavenging abilities of PPC and VC were further tested and compared with the depolymerization products to clarify the differences in scavenging efficiency among the samples.

[0084] DPPH removal rate (%) = (A 对照 -A 样品 ) / A 对照 ×100%, Among them: A 对照 The background absorbance of the blank reference system at the characteristic wavelength of 517 nm is given. A 样品 The absorbance values ​​of the condensed tannin test solution at the same wavelength are given.

[0085] Comparative Example 3 A method for preparing a ruthenium metal supported catalyst, comprising the following steps: Template preparation: Same as in Example 1.

[0086] Zirconium source impregnation: Same as in Example 1.

[0087] Metal loading: 0.2 g RuCl3 was diluted to 1 mL in a volumetric flask to obtain a RuCl3 solution; 0.64 mL of the RuCl3 solution was used as the catalyst precursor solution; the catalyst precursor solution was poured into 0.1 g ZrO2 for thorough impregnation, then freeze-dried, and then reduced with 1 mL NaBH4 solution (25 mg / mL) for 30 min. After centrifugation, washing with water, and vacuum drying at 60 °C, a ruthenium-iron bimetallic supported catalyst was obtained, denoted as Ru5 / ZrO2.

[0088] The ruthenium-iron bimetallic supported catalyst obtained in this comparative example was used to catalyze the degradation of condensed tannins. The specific steps were as follows: 0.025 g of larch bark condensed tannins (degree of polymerization 9.8) was dissolved in 10 mL of distilled water. Then, the resulting solution and 0.025 g of the (Ru2-Fe1)5 / ZrO2 catalyst prepared in this comparative example were added to a high-pressure reactor, H2 was added to 4 MPa, and the reaction was carried out at 150 °C for 3 h. The product was separated by centrifugation, and the average degree of polymerization was measured to be 4.0, with a degradation rate of 59.18%.

[0089] Figure 1 The images show the scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) spectra of the support (ZrO2) obtained in Example 1, the ruthenium-iron bimetallic supported catalysts obtained in Examples 1 and 2, and the Ru5 / ZrO2 obtained in Comparative Example 3. (a) is the SEM image of ZrO2, (b) is the SEM image of (Ru1-Fe1)5 / ZrO2, (c) is the SEM image of (Ru2-Fe1)5 / ZrO2, (d) is the SEM image of (Ru1-Fe2)5 / ZrO2, and (e) is the SEM image of Ru5 / ZrO2. f~m are the SES spectra of Zr, Ru, and Fe elements in (Ru1-Fe1)5 / ZrO2, (Ru2-Fe1)5 / ZrO2, (Ru1-Fe2)5 / ZrO2, and Ru5 / ZrO2, respectively. Figure 1 As can be seen in (a), the ZrO2 surface exhibits a uniformly distributed granular morphology, with obvious pores between the particles, as shown in the yellow box in 1(a) of the magnified local image. Figure 1 The magnified image reveals the surface details of the particles, showing their rough microstructure and pores. The pores are evenly distributed, exhibiting a uniform porous structure overall. Furthermore, the absence of significant agglomeration on the ZrO2 surface indicates a well-prepared support with a sound structural foundation. Figure 1As shown in (b) to (e), the surface morphology of Ru-Fe catalysts loaded with different proportions is significantly different from that of ZrO2 support. With the loading of Ru and Fe, the particle surface gradually becomes rough and presents an irregular shape. This indicates that the metal particles are attached to the surface after loading and may partially penetrate into the pores. Figure 1 In (b) and (d), the particle distribution is relatively uniform, and no obvious agglomeration of particles is observed; Figure 1 In (c) and (e), a slight agglomeration tendency is observed, with more compact particle spacing. Increased roughness provides more active sites, enhancing catalytic performance; however, excessive roughness may lead to particle agglomeration or partial loss of porosity, affecting the diffusion efficiency of reactants. Figure 1 As shown in f~j, the Zr element is uniformly distributed and covers the entire sample in the four catalysts, indicating that the support structure is stable. Figure 1 The scanned energy spectrum of Ru element distribution is shown in j~m. It can be seen that Ru element is uniformly distributed on the sample surface, which is consistent with the loading strategy. Moreover, Ru element is uniformly distributed in all four catalysts and there is no obvious aggregation phenomenon, indicating that the loading process is effective and can provide more active sites. Figure 1 In the diagram, n~p represents the scanning energy spectrum of Fe element distribution. The distribution characteristics of Fe element are similar to those of Ru, and it also shows good uniformity. The synergistic distribution of Ru and Fe elements provides potential synergistic sites for catalytic reactions.

[0090] Figure 2 The images show the XRD patterns of the ZrO2 obtained in Example 1, the Ru5 / ZrO2 obtained in Comparative Example 3, and the ruthenium-iron bimetallic supported catalysts obtained in Examples 1 and Comparative Examples 1-2. Figure 2The diffraction peaks of ZrO2 show distinct peaks around 30°, 35°, 50°, and 60°, corresponding to the tetragonal phase crystal structure of ZrO2. This indicates that the support has high crystallinity, and the intensity and shape of the peaks suggest uniform grain size. The XRD pattern of the catalyst after metal loading shows that the positions of the main diffraction peaks of the support remain almost unchanged, indicating that the crystal structure of ZrO2 remains stable. However, the intensity of some peaks is slightly reduced, possibly due to the metal adhesion covering the ZrO2 grain surface or interaction between the metal and the support surface. The diffraction peak positions of Ru5 / ZrO2 loaded only with Ru metal were basically consistent with those of the ZrO2 support, and no significant new peaks were observed. However, the peak intensities of the characteristic ZrO2 peaks near 30°, 35°, 50°, and 60° all showed a significant decrease. This is because Ru particles are distributed on the ZrO2 surface, partially obscuring the ZrO2 grains. Simultaneously, the high atomic number of Ru metal causes a certain absorption effect on X-rays, thereby reducing the diffraction intensity of the ZrO2 phase and weakening the X-ray diffraction signal of ZrO2. This typically occurs under conditions of high metal loading (in the case of Ru5) and uniform metal particle coverage of the support surface. However, as the Ru metal loading ratio decreases, the ZrO2 characteristic peaks corresponding to the XRD patterns of (Ru2-Fe1)5 / ZrO2, (Ru1-Fe1)5 / ZrO2, and (Ru1-Fe2)5 / ZrO2 gradually increase at angles of 30°, 35°, 50°, and 60°. This is because the absorption effect of Ru metal on X-rays gradually weakens with the decrease in the Ru metal loading ratio. Furthermore, no diffraction characteristic peaks of Ru and Fe metals were observed in any of the catalysts. This is because Ru and Fe metal particles are mainly highly dispersed and nanoscale-sized on the ZrO2 support surface, resulting in a failure to reach the XRD detection limit, which may be beneficial for improving catalytic performance.

[0091] Figure 3 The images show TEM images of the ZrO2 and (Ru1-Fe1)5 / ZrO2 carriers obtained in Example 1 at different magnifications: (a) ZrO2, 200,000×; (b) ZrO2, 800,000×; (c) (Ru1-Fe1)5 / ZrO2, 200,000×; (d) (Ru1-Fe1)5 / ZrO2, 800,000×. Figure 3 As can be seen in (a), the ZrO2 nanoparticles exhibit a relatively dispersed microstructure, accompanied by a porous structure. Figure 3 The yellow circles in (b) show the ordered porous structure of ZrO2, which provides an ideal loading platform for subsequent active metal dispersion; while Figure 3In (c), after modification with Ru and Fe, the particles became more compact, indicating that the introduction of the active metal significantly altered the catalyst's microstructure and increased the contact probability between particles. Figure 3 High-resolution analysis in (b) shows a clear distribution of ZrO2 lattice fringes and consistent interplanar spacing, further indicating that ZrO2 possesses good crystallinity and an ordered porous structure, which is beneficial for the adsorption and diffusion of reactant molecules. Furthermore, in Figure 3 In (d), it can be seen from the interplanar spacing that the (205) crystal plane of Ru, the (211) crystal plane of Ru2O3 and the (104) crystal plane of Fe2O3 are all exposed on the ZrO2 surface. They work synergistically with the ordered pores and high specific surface area of ​​ZrO2 to improve the reaction performance and stability of the catalyst.

[0092] Figure 4 XPS spectra of the ruthenium-iron bimetallic supported catalyst ((Ru1-Fe1)5 / ZrO2) obtained in Example 1 are shown in (a) as the full spectrum, (b) as the fine spectrum of Fe 2p, and (c) as the fine spectrum of Ru 3p. From (a) of Figure 4, it can be seen that the (Ru1-Fe1)5 / ZrO2 catalyst mainly contains elements such as O, Ru, Fe, Zr, and C; among them, O 1S appears near 530 eV, indicating that there is abundant oxygen on the ZrO2 surface, corresponding to its oxide substrate structure. Ru 3p is visible in the range of 460~480 eV, indicating the presence of Ru element. Figure 4 (c) can be further analyzed for its valence state. Fe 2p is visible in the range of 710–730 eV, indicating the presence of Fe. Figure 4 (b) can be further analyzed for its valence state. Combined with... Figure 4 As shown in (a), Zr 3d is in the range of 180~200 eV, indicating that ZrO2 has obvious matrix characteristics, and C 1s is around 285 eV, which is a common characteristic peak of surface carbon contamination.

[0093] from Figure 4 As can be seen from the fine Fe spectrum in (b), Fe in the catalyst of this invention... 3+ and Fe 0 Coexistence; of which Fe 2p 3 / 2 The peak is located around 710 eV, corresponding to Fe 3+ The presence of Fe 2p may be a characteristic of iron oxide. 1 / 2 The peak splits around ~723 eV, which also corresponds to Fe. 3+ And it shows clear peaks for oxidation states; Fe 3+ The satellite structure of the characteristic peaks is clearly visible near 715 eV and 730 eV, further confirming Fe.3+ The presence of Fe was detected in the range of 707–709 eV. 0 The peak indicates that some iron is a zero-valent metal, possibly representing reduced Fe elemental form or an alloy, while Fe... 0 The characteristic peaks of Fe are relatively narrow and there is no obvious satellite structure, indicating that its electronic state is relatively stable. 3+ The presence of Fe can enhance Lewis acidity, promote substrate adsorption and polarization, especially its effect on C / C bond breaking; 0 It provides electron donor properties, which may synergize with the hydrogen activation sites of Ru to improve the efficiency of hydrogenolysis reaction.

[0094] Figure 4 As can be seen from the fine Ru spectrum in (c), Ru in the catalyst of this invention... 3+ and Ru 0 Coexistence; among them, there are two distinct peaks at approximately 462 eV and 485 eV, which correspond to metallic ruthenium (Ru). 0 The 3p electron binding energy of Ru is shown in the figure, and these two peaks are relatively sharp and intense. This is because metallic Ru has a high electron density, and the 3p electron binding energy is relatively stable. There are two peaks near approximately 467 eV and 480 eV, which correspond to the oxidation state of Ru (Ru). 3+ The 3p electron binding energy of Ru is relatively broad and has low intensity. This is because the chemical environment of oxidized Ru is more complex, with a lower electron density, resulting in a wider distribution of 3p electron binding energies. In the catalyst of this invention, Ru mainly exists in the metallic state (Ru...). 0 ) and a small amount of oxidation state (Ru) 3+ ) exists, Ru 0 It provides strong hydrogen adsorption and dissociation capabilities, which are crucial for hydrogen activation. Ru 0 The presence of Ru also facilitates electron transfer, further optimizing the catalyst's activity towards the substrate through synergy with Fe and ZrO2; 3+ The presence of this indicates that some ruthenium on the surface may be transformed into an oxidized state due to the oxidation of ZrO2, which further enhances the Lewis acid sites on the catalyst surface.

[0095] XPS full spectrum and peak analysis revealed that the (Ru1-Fe1)5 / ZrO2 catalyst exhibited a significant multivalent synergistic effect. 0 and Fe 0 It provides active hydrogen generation sites, enhancing hydrogen hydrolysis efficiency through strong adsorption and dissociation of hydrogen gas, while Ru 3+ and Fe 3+The oxidation state of the catalyst enhances the Lewis acidity of the catalyst surface, which is beneficial for substrate adsorption, CC polarization, and the regulation of the reaction pathway. Furthermore, ZrO2, as a stable support, not only provides abundant acidic sites to further lower the energy barrier for CC bond breaking, but also optimizes the electronic structure and dispersion of the active centers through interfacial interactions with Ru and Fe. The multivalent combination of Ru, Fe, and ZrO2 achieves functional complementarity of the active sites, providing a strong catalytic basis for the efficient hydrogenolysis of condensed tannins.

[0096] Figure 5 This is a comparative graph showing the DPPH· free radical scavenging activities of PPC, LOPC, and VC. Figure 5 As shown, LOPC exhibits significantly higher scavenging rates than PPC and VC at all concentrations. This is likely because LOPC, as a degradation product, may generate more compounds with simpler structures and higher phenolic hydroxyl exposure during degradation, such as oligomeric proanthocyanidins or monomeric phenolic compounds. These molecules possess stronger electron-donating or hydrogen-donating capabilities, enabling more efficient reduction of DPPH· and thus demonstrating significantly higher scavenging efficiency. VC shows the second highest scavenging ability, consistent with its performance as a classic antioxidant, while PPC exhibits the lowest scavenging ability, possibly related to the steric hindrance effect caused by its complex condensation structure, which limits the contact between the active groups and DPPH·. In summary, the superior performance of LOPC indicates that degradation using a (Ru1-Fe1) / ZrO2 catalyst can significantly enhance its antioxidant properties.

[0097] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A ruthenium-iron bimetallic supported catalyst for the catalytic degradation of condensed tannins, characterized in that, Mesoporous zirconium dioxide was used as a support, and ruthenium and iron bimetals were loaded as catalytic active components. The total loading of the ruthenium-iron bimetallic compound is 5-6 wt%. The molar ratio of ruthenium to iron is 1:

1.

2. The ruthenium-iron bimetallic supported catalyst for the catalytic degradation of condensed tannins according to claim 1, characterized in that, The total loading of the ruthenium-iron bimetal is 5.4~6 wt%.

3. A method for preparing a ruthenium-iron bimetallic supported catalyst for the catalytic degradation of condensed tannins as described in any one of claims 1 to 2, characterized in that, Includes the following steps: S1. Dissolve the triblock copolymer Pluronic P123 in a mixed solution of water and hydrochloric acid, then add tetraethyl orthosilicate dropwise, stir and react, subject the white suspension after reaction to hydrothermal treatment, filter and dry the resulting mesoporous silica composite material, and treat the resulting solid with nitric acid solution and hydrogen peroxide under reflux, wash and dry to obtain SBA-15-OH molecular sieve template. S2. After dissolving ZrOCl2·8H2O in dilute hydrochloric acid solution, it is mixed with the SBA-15-OH molecular sieve template by a proportional impregnation method, aged, then calcined, and finally etched with sodium hydroxide solution to remove silicon, washed and dried to obtain ZrO2. S3. Mix Fe(NO3)3•9H2O solution and RuCl3 solution evenly to use as catalyst precursor solution; The catalyst precursor solution was poured into ZrO2 for thorough impregnation, then freeze-dried, reduced with sodium borohydride solution, centrifuged, washed with water, and vacuum dried to obtain the ruthenium-iron bimetallic supported catalyst for catalytic degradation of condensed tannins.

4. The method for preparing the ruthenium-iron bimetallic supported catalyst for catalytic degradation of condensed tannins according to claim 3, characterized in that, In step S1, the mass ratio of the triblock copolymer Pluronic P123 to tetraethyl orthosilicate is 4:8.

5.

5. The method for preparing the ruthenium-iron bimetallic supported catalyst for the catalytic degradation of condensed tannins according to claim 3, characterized in that, In step S1, the stirring reaction is carried out at a temperature of 38°C for 24 hours. The hydrothermal treatment was performed at a temperature of 110 °C for 24 h. The reflux treatment was performed at a temperature of 80 °C for 3 hours.

6. The method for preparing the ruthenium-iron bimetallic supported catalyst for catalytic degradation of condensed tannins according to claim 3, characterized in that, In step S2, the mass ratio of ZrOCl2·8H2O to SBA-15-OH molecular sieve template is 4:

1.

7. The method for preparing the ruthenium-iron bimetallic supported catalyst for the catalytic degradation of condensed tannins according to claim 3, characterized in that, In step S2, the aging process is as follows: first aging at 50 ℃ for 24 h, and then aging at 90 ℃ for 48 h; The calcination treatment is as follows: at 1 °C·min -1 The calcination rate was increased to 500 °C for 5 h.

8. The method for preparing the ruthenium-iron bimetallic supported catalyst for the catalytic degradation of condensed tannins according to claim 3, characterized in that, In step S3, the concentration of the Fe(NO3)3•9H2O solution is 0.2 g / mL; the concentration of the RuCl3 solution is 0.2 g / mL.

9. The application of a ruthenium-iron bimetallic supported catalyst as described in any one of claims 1 to 2 for the catalytic degradation of condensed tannins.

10. The application according to claim 9, characterized in that, The amount of ruthenium-iron bimetallic supported catalyst added is 0.25~0.5g / 1g condensed tannin; the degradation temperature is 150 ℃, the time is 3 h, and the pressure is 4 MPa.

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