A stable high-valent ruthenium photothermal catalyst and its preparation method and application

Abstract

The present invention discloses a stable high-valent ruthenium photothermal catalyst and its preparation method and application, which belongs to the field of catalysis technology. The tunnel structure titanate is dispersed into RuCl3 solution and stirred, filtered and washed to obtain Ru 3+ intercalated titanate; Ru 3+ The embedded titanate is placed in a closed environment containing H2 and CO2 gas for photothermal activation to obtain titanate-supported ruthenate, which is a stable high-valent ruthenium photothermal catalyst. δ+ site, targeting Ru δ+ The site is easily reduced during the photothermal catalytic CO2 methanation process, and Ru is anchored by layered titanate. δ+ The catalytic site, combined with the coordination effect of alkali metals, significantly improves Ru δ+ The photothermal catalytic stability and activity of the catalyst are improved, solving the problem of unstable catalytic sites in existing photothermal catalysts. The methane yield and CO2 conversion rate in CO2 methanation are greatly improved.

Description

Technical Field

[0001] The present invention relates to the field of catalysis technology, and in particular to a stable high-valent ruthenium photothermal catalyst and a preparation method and application thereof. Background Art

[0002] In the coming years, reducing carbon dioxide emissions and striving for sustainable development are urgent tasks, and photothermal catalysis is a very promising technology to solve this problem. Photothermal catalytic CO2 methanation reduces the activation energy of the reaction through the synergistic effect of photochemistry and thermochemistry, thereby achieving efficient conversion of CO2 to methane at lower temperatures and pressures, significantly improving energy utilization efficiency, and providing an innovative path for CO2 resource utilization. In order to achieve efficient photothermal catalytic CO2 methanation, it is necessary to controllably synthesize catalysts with high photothermal conversion performance and rationally design the CO2 activation and hydrogenation sites of the catalyst. In addition, it is particularly important that the stability of the catalytic site is the key to determining whether the catalyst photothermal CO2 resource utilization can be practically applied.

[0003] Among different metal catalysts, Ru is the metal with the highest comprehensive activity. For example, the patent with application number CN 112371117 A discloses a highly dispersed ruthenium-loaded surface-modified layered titanate nanosheet photocatalyst, a preparation method and its application. The highly dispersed ruthenium-loaded surface-modified layered titanate nanosheet photocatalyst Ru@HST is prepared by hydrothermal reaction and calcination. "Preparation and Application of Two-Dimensional Layered Highly Dispersed Metal Catalysts" (Li Lu, Master's thesis, 2017) uses the traditional solid-phase method to prepare layered titanium oxide nanomaterials, and then uses the ion exchange method to prepare Ru / HTiO catalysts. In the above catalysts, Ru exists in the form of a single substance, and in the catalytic production of methane from CO2 and H2, the catalytic performance of zero-valent ruthenium is not as good as that of high-valent ruthenium (Ru δ+ This is because high-valent ruthenium (Ru δ+ ) is a more active catalytic site, Ru δ+ The site can introduce new Lewis active sites, which is beneficial to the activation of CO2 at low temperature. However, since the CO2 hydrogenation reaction usually uses a hydrogen-rich atmosphere, Ru δ+ The stability in hydrogen-rich atmosphere is low and it is easily reduced. For example, Layered Na2Ti3O7-supported Ru catalyst for ambient CO2methanation (Hyo-Jin Kim, Nature Communications (2025) 16:2697) reported that Na2Ti3O 17 and RuCl 3· xH2O was prepared by hydrothermal reaction to obtain Ru x Ti y O zAs a catalyst for photothermal catalytic CO2 methanation, but the Ru in the catalyst δ+ Unstable, it is reduced to zero-valent ruthenium when the CO2 methanation photocatalysis is carried out at 180 ° C, and Ru δ+ It is crucial to explore new strategies that can stabilize Ru in its oxidized state and inhibit the oxidation of Ru. δ+ The reduction of the sites remains a challenge. Therefore, a stable high-valent ruthenium photothermal catalyst is needed that can maintain a high valence state and not be reduced even when subjected to photocatalytic reactions at temperatures exceeding 300 degrees Celsius, thereby improving the catalytic efficiency of CO2 methanation. Summary of the Invention

[0004] In view of the above existing technologies, the purpose of the present invention is to provide a stable high-valent ruthenium photothermal catalyst and its preparation method and application. δ+ site, targeting Ru δ+ The site is easily reduced during the photothermal catalytic CO2 methanation process, and the tunnel structure titanate is used to anchor Ru δ+ The catalytic site, combined with the coordination effect of alkali metals, significantly improves Ru δ+ The photothermal catalytic stability and activity are improved, solving the problem of unstable catalytic sites in existing photothermal catalysts.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] The first aspect of the present invention provides a method for preparing a stable high-valent ruthenium photothermal catalyst, comprising the following steps:

[0007] (1) Disperse the tunnel structure titanate into RuCl3 solution and stir, filter and wash to obtain Ru 3+ intercalated titanates;

[0008] (2) Ru 3+ The embedded titanate is placed in a closed environment containing H2 and CO2 gases for photothermal activation to obtain titanate-loaded ruthenate, which is a stable high-valent ruthenium photothermal catalyst.

[0009] Preferably, in step (1), the tunnel structure titanate is K2Ti6O 13 (KTO).

[0010] Preferably, the K2Ti6O 13 Prepared by hydrothermal reaction, the specific method is:

[0011] TiO2 powder was dispersed in KOH aqueous solution, and hydrothermal reaction was carried out. The precipitate was collected and washed to obtain K2Ti6O 13 .

[0012] Preferably, the mass ratio of the TiO2 powder to KOH is 1:90; and the concentration of the KOH aqueous solution is 10 M.

[0013] Preferably, the temperature of the hydrothermal reaction is 200° C. and the time is 72 h.

[0014] Preferably, in step (1), the molar ratio of the titanate to RuCl3 is 2:1; the concentration of the RuCl3 solution is 8 mM; the stirring temperature is room temperature, and the stirring time is 24 h.

[0015] Preferably, in step (2), the volume ratio of H2 to CO2 is 4:1.

[0016] Preferably, in step (2), the photothermal activation is performed using a 300 W xenon lamp with a plano-convex lens at 2.0 W cm -2 Irradiate with the intensity of 1h.

[0017] The second aspect of the present invention provides a stable high-valent ruthenium photothermal catalyst obtained by the above preparation method, wherein the high-valent ruthenium photothermal catalyst is K2Ti6O 13 Loaded K2RuO3.

[0018] The third aspect of the present invention provides the use of a high-valent ruthenium photothermal catalyst in improving the catalytic performance of photothermal catalytic CO2 methanation.

[0019] Preferably, the catalytic performance is the yield of methane and the conversion rate of CO2.

[0020] Beneficial effects of the present invention:

[0021] (1) The present invention uses titanate with tunnel structure as a carrier to construct Ru δ+ site, targeting Ru δ+ The site is easily reduced during the photothermal catalytic CO2 methanation process, and the tunnel structure titanate is used to anchor Ru δ+ The catalytic site, combined with the coordination effect of alkali metals, significantly improves Ru δ+ The photothermal catalytic stability and activity are improved, solving the problem of unstable catalytic sites in existing photothermal catalysts.

[0022] (2) The preparation method of the present invention is simple, and the prepared catalyst has an ultra-high photothermal CH4 generation rate and a high CO2 conversion rate, and exhibits excellent stability in the entire photothermal CO2 methanation process, and has significant activity and Ru δ+ Inhibitory effect of reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1:(a) XRD patterns of KTO and KTO-K2RuO3 samples, SEM images of KTO (b) and KTO-K2RuO3 (c) samples, (d) high-resolution TEM of a single nanowire in the KTO-K2RuO3 sample at a scale of 50 nm, (e) high-resolution TEM of a single nanowire in the KTO-K2RuO3 sample at a scale of 5 nm, (f) magnified HAADF-STEM image of the KTO-K2RuO3 sample;

[0024] Figure 2 :(a) Ru 3d high-resolution XPS spectra of KTO and KTO-K2RuO3,(b) Ti 2p high-resolution XPS spectra of KTO and KTO-K2RuO3,(c) K 2p high-resolution XPS spectra of KTO and KTO- K2RuO3,(d) Ru K-edge XANES spectra of KTO- K2RuO3, Ru foil (from standard sample) and RuO2,(e) FT-EXAFS spectra of KTO- K2RuO3, Ru foil and RuO2,(f) Ti K-edge XANES spectra of KTO, KTO- K2RuO3, Ti foil (from standard sample) and TiO2,(g) FT-EXAFS spectra of KTO, KTO- K2RuO3, Ti foil and TiO2,(h) Ru K-edge WT-EXAFS spectra of KTO- K2RuO3, Ru foil and RuO2 and KTO, KTO- Ti K-edge WT-EXAFS of K2RuO3 and TiO2;

[0025] Figure 3 :(a) UV-Vis-NIR absorption spectra of KTO and KTO-K2RuO3,(b) temperature curves of KTO and KTO-K2RuO3,(c) infrared thermal imaging photos of KTO and KTO-K2RuO3;

[0026] Figure 4 : (a) Stability of KTO-K2RuO3 in terms of CH4 yield, CH4 selectivity, and CO2 conversion, (b) Stability of HTO-RuO2 catalyst in terms of CH4 yield, CH4 selectivity, and CO2 conversion (gas flow rate: 35 mL min -1 , light intensity: 2.72 W cm -2 );

[0027] Figure 5:(a) Ru 3d5 / 2 high-resolution XPS spectra and crystal structure model schematic of KTO-K2RuO3 and HTO-RuO2 before and after stability test,(b) XRD patterns of KTO-K2RuO3 and HTO-RuO2 before and after stability test,(c) TEM patterns of KTO-K2RuO3 before and after stability test,(d) in situ FTIR spectra of KTO-K2RuO3 and HTO-RuO2 corresponding to H / D exchange experiment;

[0028] Figure 6 : Comparison of photothermal catalytic CH4 yield and CH4 selectivity of the catalysts prepared by KTO-K2RuO3 and Comparative Examples 1 to 3;

[0029] Figure 7 : Schematic diagram of the mobile phase photothermal catalytic reactor system. DETAILED DESCRIPTION

[0030] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0031] As introduced in the background technology section, the catalytic performance of ruthenium metal in catalyzing CO2 methanation is not as good as that of Ru δ+ 。 δ+ The sites can introduce new Lewis active sites for CO2 activation at low temperatures. However, due to their low stability in hydrogen-rich atmosphere, they are easily reduced. This is because, during the catalytic hydrogenation process, H2 can be δ+ -O 2- Interfacial heterogeneous cracking to form hydrides (Ru-H δ- ) and protons (OH δ+ ), or at a low price δ+ However, the split hydrogen is highly reactive and not only participates in the hydrogenation of CO2, but also converts the positively charged Ru δ+ The substance is reduced to metallic Ru 0 , which reduces the catalytic performance.

[0032] Based on this, the purpose of the present invention is to provide a stable high-valent ruthenium photothermal catalyst and its preparation method and application. 13 With a tunnel structure, the alkali metal coordination in potassium titanate can form ruthenate (potassium ruthenate) to stabilize Ru δ+ Status. δ+The excellent stability of the prepared photothermal catalyst can be attributed to the high Ru-O bond strength in the formed potassium ruthenate and the stabilizing effect of the K base on the cracked H species. Without the need for external heating, the prepared photothermal catalyst exhibited significant photothermal catalytic activity and stability in the conversion of CO2 to CH4, with a CH4 selectivity of over 99.9%. δ+ As Lewis active sites, the activation energy of the reaction is reduced, and titanate-Ru δ+ The CO2 hydrogenation pathway of the photothermal catalyst tends to be more favorable to the formate pathway. In addition, the presence of K element can act as an alkali aid, which not only promotes the adsorption of CO2, but also stabilizes the H generated by dissociation on the metal site, effectively inhibiting the high-valent ruthenium Ru δ+ Moreover, the tunnel structure of potassium titanate K2Ti6O 13 The carrier has a large specific surface area, can provide sufficient sites for active components, has low thermal conductivity, good thermal insulation effect, high temperature resistance, and good stability, making it a good photothermal catalyst carrier.

[0033] The titanate-supported ruthenate photothermal catalyst was prepared into an ultra-thin inorganic porous nanopaper. By utilizing the full contact between the porous nanopaper, the flowing gas and the solar radiation, the designed mobile phase reactor system achieved an ultra-high photothermal CH4 generation rate and a high CO2 conversion rate. Overall, the titanate-supported ruthenate photothermal catalyst showed excellent stability throughout the photothermal CO2 methanation process, with significant activity and Ru δ+ Inhibitory effect of reduction.

[0034] In order to enable those skilled in the art to more clearly understand the technical solution of the present application, the technical solution of the present application will be described in detail below with reference to specific embodiments.

[0035] The test materials used in the examples of the present invention are all conventional test materials in the art and can be purchased through commercial channels.

[0036] Example 1: K2Ti6O 13 Preparation of loaded K2RuO3 (KTO-K2RuO3)

[0037] (1) Synthesis of titanate nanowire carriers by hydrothermal method

[0038] 0.50 g of commercially available TiO2 powder (P25) was dispersed in 80 mL of 10 M KOH aqueous solution and then transferred to a 100 mL polytetrafluoroethylene-lined hydrothermal autoclave, heated to 200°C and maintained at this temperature for 72 hours. After the reaction was completed, the precipitate was collected and thoroughly washed with deionized water and dried in an oven at 60°C to obtain K2Ti6O 13 nanowires (KTO).

[0039] (2) K2Ti6O obtained in step (1) 13 The nanowires were dispersed in 1 mL of 8 mM RuCl3 solution (K2Ti6O 13 The molar ratio of RuCl3 was 2:1) and the ion exchange reaction was carried out and stirred for 24 hours. After the reaction was completed, it was filtered, washed with deionized water several times, and dried to obtain Ru 3+ Embedded titanate nanowires.

[0040] (3) The Ru obtained in step (2) 3+ The embedded titanate nanowires were placed in a transparent sealed container filled with a mixture of H2 and CO2 (volume ratio 4:1) and illuminated by a 300 W xenon lamp with a plano-convex lens (spot diameter 3 cm, intensity 2.0 W cm -2 , corresponding to the photothermal temperature of 255℃) through a transparent sealed container to irradiate Ru 3+ The embedded titanate nanowires were photothermally activated for 1 h to obtain KTO-K2RuO3.

[0041] Comparative Example 1: H2Ti6O 13 Preparation of loaded RuO2

[0042] (1) The K2Ti6O obtained in step (1) of Example 1 was 13 The nanowires were dispersed in 200 mL of 0.1 M HCl solution for proton exchange reaction and stirred for 48 h. After the reaction, the solution was filtered, washed with deionized water several times, and dried to obtain a titanate nanowire support denoted as HTO.

[0043] (2) By thermal decomposition of ruthenium carbonyl (Ru3(CO) 12 ) Preparation of H2Ti6O 13 Carrier-loaded RuO2 (HTO-RuO2)

[0044] 10 mg of HTO nanowires were immersed in 0.68 mL of 2.5 mg mL -1 Ru3(CO) 12 In acetone solution (to ensure the same Ru element loading as KTO-K2RuO3), after stirring and drying, the mixture was irradiated with an infrared lamp (0.9W cm -2 ) was thermally decomposed for 10 min to obtain H2Ti6O 13 The loaded RuO2 is recorded as HTO-RuO2.

[0045] Comparative Example 2: Preparation of TiO2-loaded RuO2

[0046] (1) The HTO nanowires obtained in step (1) of comparative example 1 were calcined at 600°C for 2 h in an air atmosphere to obtain TiO2 nanowires.

[0047] (2) By thermal decomposition of ruthenium carbonyl (Ru3(CO) 12 ) to prepare TiO2-supported RuO2 (TiO2-RuO2). 10 mg TiO2 nanowires were immersed in 0.68 mL 2.5 mg mL -1 Ru3(CO) 12 In acetone solution (to ensure the same Ru element loading as KTO-K2RuO3), after stirring and drying, the mixture was irradiated with an infrared lamp (0.9 W cm -2 ) was thermally decomposed for 10 min to obtain TiO2 loaded with RuO2, which was recorded as TiO2-RuO2.

[0048] Comparative Example 3: K2Ti6O 13 Preparation of loaded Ru

[0049] Under pure H2 atmosphere, the KTO-K2RuO3 sample prepared in Example 1 was thermally reduced at 600℃ for 2h to obtain K2Ti6O 13 The metal Ru catalyst on the 0 .

[0050] Example 2: Characterization

[0051] Figure 1 In (a), the KTO-K2RuO3 prepared in Example 1 was characterized by XRD. It can be seen that KTO exhibits crystalline K2Ti6O 13 Phase (JCPDS card number 40-0403), its characteristic diffraction peaks 11.5° correspond to (200) crystal plane, 24.1° correspond to (110) crystal plane, 29.3° correspond to (310) crystal plane, 32.0° correspond to (112) crystal plane, 43.5° correspond to (602) crystal plane, 47.9° correspond to (020) crystal plane. The XRD pattern of KTO-K2RuO3 shows that it is similar to K2Ti6O 13 In agreement with the results, no additional peaks appeared, indicating that the loading amount of Ru was low. Figure 1 The SEM images of KTO and KTO-K2RuO3 show that KTO has not changed significantly from a slender and uniform nanowire morphology to KTO-K2RuO3, with a width of tens of nanometers and a length of several microns. It can be seen that the surface of KTO nanobelts is smooth, while the surface of KTO-K2RuO3 is slightly rough. Further transmission electron microscopy (HRTEM) characterization of the samples revealed that after the photothermal activation process, Figure 1Middle (e) KTO-K2RuO3 clearly presents ultrasmall nanoparticles with a size of 2-4 nm anchored on the nanowires, indicating the formation of K2RuO3 on KTO. Figure 1 The high-resolution HAADF-STEM image after spherical aberration correction in (f) shows that the lattice fringe spacing of the supported particles is 0.246 nm, which is consistent with the lattice fringe of the K2RuO3 (410) crystal plane. 13 The lattice fringes corresponding to the carrier (310) crystal plane can also be observed.

[0052] To gain a deeper understanding of the surface chemical state and electronic structure of KTO-K2RuO3, X-ray photoelectron spectroscopy (XPS) spectra and X-ray absorption near-edge spectroscopy (XANES) spectra were further investigated. Figure 2 (a) shows the high-resolution XPS spectrum of Ru 3d. 3 / 2 The peak and C 1s peak appear in the same binding energy region, so they will be affected. 5 / 2 The comparison of XPS peaks is more obvious. After photothermal activation, Ru 3d 5 / 2 The combined peak at 280.4 eV is associated with Ru 4 + Good correspondence. Figure 2 As shown in (b), for K2Ti6O 13 and KTO-K2RuO3, the corresponding Ti 2p 3 / 2 and Ti 2p 1 / 2 Two characteristics Ti 4+ Peak. Compared with KTO, the Ti 2p of KTO-K2RuO3 3 / 2 The XPS peak is slightly negatively shifted, indicating that there is electron transfer between KTO and K2RuO3. Figure 2 In the Ru K-edge XANES spectrum shown in (d), the white line energy of KTO-K2RuO3 is higher than that of Ru foil (standard sample from synchrotron radiation), lower than but very close to RuO2. Combined with the magnified HAADF-STEM results, it is found that the Ru in KTO-K2RuO3 mainly exists in the form of high-valent K2RuO3. Figure 2 As shown in (e), the FT-EXAFS pattern of KTO-K2RuO3 shows that the Ru-O coordination at 1.5Å is dominant. This is also consistent with the anchoring of K2RuO3 nanoparticles on K2Ti6O 13 The results on nanowires are consistent.

[0053] The light absorption and photothermal conversion capabilities of the catalyst were verified by UV-Vis-NIR absorption spectroscopy and infrared thermal imaging. Figure 3As shown in (a), the KTO support exhibits a clear absorption edge near 370 nm with a corresponding band gap of ~3.4 eV, while KTO-K2RuO3 shows excellent adsorption throughout the entire UV-Vis-NIR spectrum. Figure 3 (b) and Figure 3 (c) shows the xenon lamp intensity of 2.72 W cm during the catalytic CO2 methanation process. -2 The photothermal temperature and corresponding infrared thermal image under irradiation conditions are shown. The surface temperature of KTO-K2RuO3 increases rapidly within 10 seconds, reaching a photothermal temperature of 312.6°C. This is higher than the temperature of KTO (71.2°C) under the same irradiation conditions, indicating that K2RuO3 plays a major role in light absorption and photothermal conversion.

[0054] Test Example 1: Catalytic stability and structural stability test

[0055] The experiment was divided into two groups: KTO-K2RuO3 prepared in Example 1 and HTO-RuO2 prepared in Comparative Example 1.

[0056] (1) Using a homemade reactor with a quartz window (such as Figure 7 The catalytic stability test was conducted using a flow reactor system (shown). 10 mg of KTO-K2RuO3 nanowires were dispersed in 5 mL of ethanol and filtered to form inorganic porous nanopaper, which was directly used as the support and catalyst in the flow reactor system. The filtered sample was placed in the middle mesh layer, and a volume of 20 mL of gas (20% CO2, 80% H2) was injected into the reaction chamber. The gas flowed in from the bottom to fully contact the catalyst, and then the reaction was continued at a rate of 15-35 mL min. -1 The gas flowed out from the top at a speed of 1.5 %. A 300 W Xe lamp with a plano-convex lens (spot diameter 3 cm, intensity 2.72 W cm) was used. -2 The photothermal reaction was driven by a temperature of 312.6°C (corresponding to a photothermal temperature of 312.6°C) for 400 min. Offgas was collected every 20 min and analyzed using a gas chromatograph (HuiFen-901 analyzer) equipped with a thermal conductivity detector (TCD) and a flame ionization detector (FID).

[0057] (2) Structural stability was characterized by testing the Ru 3d structure of the sample before and after the catalytic stability reaction. 5 / 2 The results were verified by XPS, XRD, TEM and in situ Fourier transform infrared spectroscopy (FTIR) H / D exchange experiments.

[0058] (3) Figure 4-Figure 5The catalytic stability and structural stability of KTO-K2RuO3 are shown. The photothermal catalytic performance and phase structure of the KTO-K2RuO3 sample remained stable during the subsequent photothermal catalytic process. During the 400-minute photothermal CO2 methanation operation of the mobile phase catalysis, the tail gas was collected every 20 minutes for detection. Figure 4 It showed that no obvious decrease in CH4 yield and CO2 conversion was detected, indicating that KTO-K2RuO3 maintained high efficiency and stability. Figure 5 Showing Ru 3d before and after photothermal catalytic reaction 5 / 2XPS, XRD and TEM characterization confirmed the structural stability of KTO-K2RuO3, and there was no Ru before and after the reaction. &+ The reduction and phase and morphology changes of HTO-RuO2 were observed. However, the performance of HTO-RuO2 could not remain stable and declined. The XPS spectrum of Ru 3d after photothermal catalysis also showed that RuO2 was reduced to metallic Ru. In situ Fourier transform infrared spectroscopy (FTIR) H / D exchange experiments showed that after treatment in D2 (deuterium) at 310 °C, KTO-K2RuO3 had a peak at ~2300-2800 cm -1 Surface-OD x In contrast, no significant -OD was detected on HTO-RuO2 treated under the same conditions. x signal, which is due to dehydration resulting in -OD x The material has poor stability at high temperatures. Dehydration means that the hydride species migrate to the interfacial oxygen, resulting in Ru δ+ Therefore, this result can prove that the presence of K ions can stabilize and inhibit the reduction of Ru δ+ Restoration.

[0059] Test Example 2

[0060] The experiment was divided into 5 groups: KTO-K2RuO3 prepared in Example 1, KTO prepared in step (1) of Example 1, HTO-RuO2 prepared in Comparative Example 1, TiO2-RuO2 prepared in Comparative Example 2, KTO-RuO2 prepared in Comparative Example 3 0 First, 10 mg of the catalyst of each group was weighed and filtered onto a quartz fiber membrane and dried at room temperature. The stability test conditions of Experimental Example 1 were consistent, and KTO, KTO-K2RuO3, KTO-Ru 0 The concentrations of CH4 and CO in the tail gas of , HTO-RuO2, and TiO2-RuO2 after photothermal catalytic reaction for 20 min were measured to calculate the CH4 yield and CH4 selectivity.

[0061] Figure 6It is shown that the KTO support exhibits negligible catalytic activity due to its relatively low photothermal temperature (71.2 °C) and inert nature. 0 The catalyst showed higher activity and high CH4 selectivity (~99.99%), confirming the positive role of Ru in promoting photothermal catalytic CO2 methanation. At the same photothermal temperature of 312.6℃, the CH4 yield of KTO-K2RuO3 (992.3 mmol g cat -1 h -1 ) is KTO-Ru 0 (168.7 mmol g cat -1 h -1 ) performance is about 6 times that of the oxidized Ru δ+ It is the main catalytic site. To further confirm the role of the KTO support, HTO-RuO2 and TiO2-RuO2 samples were prepared while ensuring the same Ru species loading. Because HTO and TiO2 nanowires are supports, Ru exists mainly in the form of high-valent RuO2. The CH4 yields of HTO-RuO2 and TiO2-RuO2 were 653.8 mmol g, respectively. cat -1 h -1 and 605.7 mmol g cat -1 h -1 , which are lower than KTO-K2RuO3, further confirming the high photothermal catalytic activity of high-valent K2RuO3.

[0062] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A method for preparing a stable high-valent ruthenium photothermal catalyst, characterized in that: The stable high-valent ruthenium photothermal catalyst is K2Ti6O 13 Loading K2RuO3; the preparation method comprises the following steps: (1) Disperse the tunnel structure titanate into RuCl3 solution and stir, filter and wash to obtain Ru 3+ Embedded titanate; the tunnel structure titanate is K2Ti6O 13 ; (2) Ru 3+ The embedded titanate was placed in a closed environment containing H2 and CO2 gases for photothermal activation to obtain titanate-loaded ruthenate, which is a stable high-valent ruthenium photothermal catalyst; the photothermal activation was performed using a 300 W xenon lamp with a plano-convex lens at 2.0 W cm -2 Irradiate with the intensity of 1h.

2. The preparation method according to claim 1, characterized in that The K2Ti6O 13 Prepared by hydrothermal reaction, the specific method is: TiO2 powder was dispersed in KOH aqueous solution, and hydrothermal reaction was carried out. The precipitate was collected and washed to obtain K2Ti6O 13 .

3. The preparation method according to claim 2, characterized in that The mass ratio of the TiO2 powder to KOH is 1:90; the concentration of the KOH aqueous solution is 10 M.

4. The preparation method according to claim 2, characterized in that The temperature of the hydrothermal reaction is 200° C. and the time is 72 h.

5. The preparation method according to claim 1, characterized in that In step (1), the molar ratio of the titanate to RuCl3 is 2:1; the concentration of the RuCl3 solution is 8 mM; the stirring temperature is room temperature, and the stirring time is 24 h.

6. The preparation method according to claim 1, characterized in that In step (2), the volume ratio of H2 and CO2 is 4:

1.

7. The stable high-valent ruthenium photothermal catalyst obtained by the preparation method according to any one of claims 1 to 6, characterized in that: The stable high-valent ruthenium photothermal catalyst is K2Ti6O 13 Loaded K2RuO3.

8. Use of the stable high-valent ruthenium photothermal catalyst according to claim 7 in improving the catalytic performance of photothermal CO2 methanation.

9. The use according to claim 8, characterized in that The catalytic performance is the yield of methane and the conversion rate of CO2.

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