Ultrathin Ru / Co3O4 catalyst, preparation method thereof and application of ultrathin Ru / Co3O4 catalyst in photo-thermal CO2 hydrogenation

Abstract

The invention relates to an ultrathin Ru / Co3O4 catalyst, Co3O4 serving as a carrier is of an ultrathin two-dimensional nanosheet structure, and Ru nanoparticles are uniformly loaded on the surface of the Co3O4. The preparation method comprises the following steps: dispersing Co3O4 in a mixture of deionized water and methanol to obtain a suspension; and adding ruthenium trichloride into the suspension, and irradiating the mixture with a xenon lamp to finally obtain the ultrathin Ru / Co3O4 catalyst. The invention relates to an ultrathin Ru / Co3O4 catalyst applied to photo-thermal CO2 hydrogenation. The method has the advantages that Co3O4 is of an ultrathin two-dimensional nanosheet structure, Ru is evenly loaded on the surface of Co3O4, Ru / Co3O4 has the high specific surface area, rich active sites are provided, the photo-thermal catalysis CO2 hydrogenation activity is remarkably improved, the problem that an existing catalyst is low in activity is solved, parameters such as the heating rate, the roasting temperature and time are accurately controlled, and Ru doping is combined, so that the catalytic activity of CO2 is greatly improved. Active component loss and structure collapse are effectively avoided, and the stability is enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of photothermal catalysis, and in particular to an ultrathin Ru / Co3O4 catalyst, a preparation method thereof, and application in photothermal CO2 hydrogenation. Background Art

[0002] In the wave of global energy structure transformation, the demand for clean energy has surged, greenhouse gas emission reduction is urgent, and excessive carbon dioxide (CO2) emissions have caused severe environmental problems such as global climate warming and sea level rise. Under this dual pressure, the research on converting CO2 hydrogenation into high-value-added chemicals and fuels has become the focus of scientific research teams and energy companies. This direction can not only alleviate the environmental crisis, but also open up new paths for sustainable energy supply.

[0003] As an emerging technology, photothermal catalysis uses solar energy to drive chemical reactions. Compared with traditional thermal catalysis, it has significant advantages. Solar energy is clean and renewable. Using solar energy reactions can reduce dependence on traditional fossil energy and reduce carbon emissions from the source, which is in line with the concepts of green chemistry and sustainable development. At the same time, photothermal catalysis can react under mild conditions, avoiding the high requirements of high temperature and high pressure on equipment and large energy consumption, thereby significantly reducing production costs and energy consumption.

[0004] In the field of photothermal catalytic CO2 hydrogenation, existing catalysts have encountered many problems in practical applications. In terms of activity, most catalysts have low activity and poor CO2 conversion rate. A large amount of CO2 cannot be efficiently converted into target products, which not only wastes resources but also hinders large-scale industrial applications. In terms of selectivity, many catalysts find it difficult to accurately promote CO2 hydrogenation to produce specific high-value-added products, which are often accompanied by a large number of by-products, increasing the difficulty of product separation and purification and reducing the economic benefits of the reaction. Stability is also critical. During long-term reactions, some catalysts are prone to loss of active components and structural collapse, leading to deactivation and requiring frequent replacement, which increases production costs and complexity.

[0005] In recent years, ultrathin nanosheet materials have attracted widespread attention due to their unique two-dimensional structure. This two-dimensional structure gives the material an extremely high specific surface area, allowing the material to expose more active sites per unit mass. More active sites mean more effective contact between the catalyst and the reactant molecules, thereby greatly improving the reaction efficiency. Theoretically, ultrathin nanosheet materials have great potential in photothermal catalytic CO2 hydrogenation reactions and are expected to break through the bottlenecks of existing catalysts in activity, selectivity and stability. However, at present, how to obtain ultrathin nanosheet catalysts with high-efficiency photothermal performance through precise control of the preparation process and successfully apply them to CO2 hydrogenation reactions is still a difficult problem that needs to be overcome in this field. A lot of research work has focused on exploring suitable preparation methods and optimizing the composition and structure of materials to achieve this goal, but no satisfactory breakthrough has been made so far. SUMMARY

[0006] The technical problem solved by the present application is to provide an ultrathin Ru / Co3O4 catalyst, a preparation method and application in photo-thermal CO2 hydrogenation, so as to solve the problems of low activity and poor selectivity of photo-thermal catalysts in CO2 hydrogenation reaction in the prior art.

[0007] The technical solution of the present application to solve the above technical problem is as follows: An ultrathin Ru / Co3O4 catalyst, wherein the Co3O4 as a carrier in the ultrathin Ru / Co3O4 catalyst is an ultrathin two-dimensional nanosheet structure, and Ru nanoparticles are uniformly loaded on the surface thereof.

[0008] Based on the above technical solution, the present application further provides a preparation method of the ultrathin Ru / Co3O4 catalyst, comprising the following steps: S10, synthesizing Co3O4 with an ultrathin two-dimensional nanosheet structure; S20, dispersing the Co3O4 in a mixture of deionized water and methanol to obtain a suspension; S30, under a nitrogen atmosphere, adding ruthenium trichloride to the suspension, and irradiating the mixture with a xenon lamp, to finally obtain the ultrathin Ru / Co3O4 catalyst.

[0009] On the basis of the above technical solution, the present application can be further improved as follows.

[0010] Further, the mass of the Co3O4 in S30 is 0.01g-10g, and the mass of the ruthenium trichloride is 0.001g-0.1g.

[0011] Further, the irradiation power of the xenon lamp is 10W-500W, and the mixture is stirred during the irradiation of the mixture with the xenon lamp, and the stirring time is 0.1h-12h.

[0012] Further, the irradiation of the xenon lamp is full-spectrum light irradiation, and the wavelength band is 380nm-780nm.

[0013] Further, the irradiation power of the xenon lamp is 300W, and the stirring time is 3h.

[0014] Further, the synthesis method of the Co3O4 is as follows: S11, dissolving and uniformly mixing a cobalt salt and a surfactant in an aqueous solution; S12, adding a reducing agent sodium borohydride, dissolving and uniformly mixing, and washing and vacuum drying the obtained precipitate; S13, calcining the precipitate and naturally cooling to room temperature to obtain Co3O4.

[0015] Further, the cobalt salt is a cobalt-containing soluble salt or a hydrate thereof, the cobalt-containing soluble salt or the hydrate thereof is cobalt nitrate or cobalt chloride, the surfactant is a cationic surfactant, and the cationic surfactant is cetyltrimethylammonium bromide.

[0016] Further, the heating rate during the calcination is 1-5 ℃ / min, the calcination temperature is 200-500 ℃, and the calcination time is 1-6 h.

[0017] Further, the heating rate during the calcination is 2 ℃ / min, the calcination temperature is 400 ℃, and the calcination time is 4 h.

[0018] Further, the calcination is performed in a muffle furnace.

[0019] Based on the above technical solution, the application further provides an application of the ultrathin Ru / Co3O4 catalyst.

[0020] Further, the photo-thermal catalytic conversion of CO2 by the ultrathin Ru / Co3O4 catalyst specifically includes: The ultrathin Ru / Co3O4 catalyst is dispersed in a sealed reaction container, deionized water is added, the reaction container is vacuumized, then CO2 and H2 mixed gas is introduced, and a xenon lamp is used as a full-spectrum light source to perform the photo-thermal catalytic conversion of CO2.

[0021] The application has the following beneficial effects: The Co3O4 serving as a carrier in the ultrathin Ru / Co3O4 catalyst is an ultrathin two-dimensional nanosheet structure, and Ru nanoparticles are uniformly loaded on the surface of the Co3O4, so that the Ru / Co3O4 has a high specific surface area to provide abundant active sites, and the natural formation of oxygen vacancies and surface defects can not only enhance the adsorption and activation capacity of CO2, but also serve as anchoring sites to stably load Ru nanoparticles, effectively preventing the agglomeration or loss of the Ru nanoparticles in a high-temperature photo-thermal reaction, maintaining high catalytic activity and good thermal stability. -1 -1 ​The CH4 yield is high, demonstrating its excellent performance under strong solar-driven conditions. It is more suitable for actual solar thermochemical conversion scenarios, significantly improving the photothermal catalytic CO2 hydrogenation activity, achieving efficient CO2 conversion, and solving the problem of low activity of existing catalysts. It lays the foundation for industrial application. In terms of reaction selectivity, the catalyst can accurately control the product distribution, improve the generation efficiency of high value-added products, reduce by-products, reduce the energy consumption and cost of separation and purification, and improve the overall economic benefits. During the preparation process, by optimizing the preparation process (precisely controlling parameters such as the heating rate, calcination temperature and time), and combining the Ru doping strategy, it effectively prevents the loss of active components and structural collapse, improves the stability of the catalyst, and reduces production costs and process complexity. The catalyst of the present invention is obtained by precipitation method, the process is simple, the operation is convenient, the required raw materials are inexpensive, and it has the potential for long-term recycling and industrial application. It overcomes the limitations of single photocatalysis and pure thermal catalysis, has the advantages of high efficiency, low energy consumption, and recyclability, and is in line with the sustainable development energy strategy. In the photothermal catalytic CO2 hydrogenation reaction, the catalyst usage is small and can be recycled for a long time. It has broad application prospects in the field of CO2 conversion and is suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a flow chart of the method for preparing the ultrathin Ru / Co3O4 catalyst of the present invention; Figure 2 The XRD spectra of the ultrathin Ru / Co3O4 catalysts prepared in Examples 1 to 7 of the present invention are shown; Figure 3 TEM and AFM images of the ultrathin Ru / Co3O4 catalysts prepared in Examples 1 to 7 of the present invention; Figure 4 The effect diagram of photothermal CO2 hydrogenation of the ultrathin Ru / Co3O4 catalysts prepared in Examples 1 to 7 of the present invention; Figure 5 Graphs showing surface temperature changes of the ultrathin Ru / Co3O4 catalysts prepared in Examples 1 to 7 of the present invention under full-spectrum illumination. DETAILED DESCRIPTION

[0023] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0024] Example 1 like Figure 1 As shown, a method for preparing an ultrathin Ru / Co3O4 catalyst comprises the following steps: Dissolve 0.29 g of Co(NO3)2˙6H2O and 1.82 g of CTAB in 50 mL of deionized water, stir at room temperature to obtain a uniform solution, then add 0.09 g of sodium borohydride and stir, for example, for 1 hour. Wash the resulting precipitate and then vacuum dry it, for example, at 60°C. Place the dried solid in a muffle furnace and heat it to 200°C to 500°C at a rate of 1°C / min to 5°C / min and maintain it for 1 hour to 6 hours, for example, heat it to 400°C at a rate of 2°C / min and maintain it for 4 hours, and then cool it naturally to room temperature to obtain ultrathin Co3O4. 0.1 g of Co3O4 was dispersed in a mixture of 50 mL of deionized water and 10 mL of methanol to obtain a suspension; Nitrogen is filled into the suspension, that is, under a nitrogen atmosphere, 24 mg of ruthenium trichloride is added, and then the mixture is irradiated with a xenon lamp and stirred, for example, with a 10W to 500W xenon lamp and stirred for 0.1h to 12h, and further, the mixture can be irradiated with a 300W xenon lamp and stirred for 3h, and finally an ultra-thin Ru / Co3O4 catalyst can be obtained, which is recorded as 8-Ru / Co3O4.

[0025] Example 2 The difference between this embodiment and embodiment 1 is that the amount of ruthenium trichloride is changed to 6 mg, and the obtained catalyst is recorded as 2-Ru / Co3O4.

[0026] Example 3 The difference between this embodiment and embodiment 1 is that the amount of ruthenium trichloride is changed to 12 mg, and the obtained catalyst is recorded as 4-Ru / Co3O4.

[0027] Example 4 The difference between this embodiment and embodiment 1 is that the amount of ruthenium trichloride is changed to 18 mg, and the obtained catalyst is recorded as 6-Ru / Co3O4.

[0028] Example 5 The difference between this embodiment and embodiment 1 is that the amount of ruthenium trichloride is changed to 30 mg, and the obtained catalyst is recorded as 10-Ru / Co3O4.

[0029] Example 6 The difference between this embodiment and embodiment 1 is that the amount of ruthenium trichloride is changed to 0 mg, and the obtained catalyst is recorded as Co3O4.

[0030] Example 7 The difference between this example and example 1 is that the amount of ruthenium trichloride is changed to 0.1 g, the amount of Co3O4 is 5 g, and the resulting catalyst is recorded as Ru / Co3O4-2 (the numbers before Ru / Co3O4 in Examples 1 to 6 are named according to the molar ratio, and according to the molar ratio of Ru / Co, Example 2 is the same as Example 7. To avoid confusion, the numbers of Example 7 are placed at the end).

[0031] The ultrathin Ru / Co3O4 catalyst obtained in the present invention is applied to photothermal CO2 hydrogenation, comprising the following steps: weighing 50 mg of ultrathin Ru / Co3O4 catalyst, ultrasonically dispersing it in 1 mL of deionized water to form a suspension, dropwise coating the suspension on a 2.5 cm×2.5 cm support, placing the support in a 60°C oven to dry, then transferring the support to a photothermal reactor with a volume of 100 mL, sealing it, introducing a CO2 and H2 mixed gas into the quartz reactor so that the pressure is 0.50 MPa, using a xenon lamp as a light source, and on this basis keeping the catalyst at a consistent height from the light source, obtaining light of different wavelength ranges by using filters, etc., performing a photothermal catalytic CO2 reduction reaction, sampling for testing every 3 hours, analyzing the gas products by a gas chromatograph, and determining the content of the generated products by a flame ionization detector (FID).

[0032] like Figure 2 As shown in the figure, the XRD diffraction peak shapes and positions of the seven samples correspond one to one with the Co3O4 standard PDF card. After the photodeposition of Ru nanoparticles, the XRD standard spectrum of Co3O4 shows a broadening of the peak shape and no new peaks appear, indicating that the Ru nanoparticles are successfully deposited on the Co3O4 surface.

[0033] like Figure 3 As shown in the figure, the morphology of Co3O4 is an ultra-thin two-dimensional nanosheet structure. After the deposition of photodeposited Ru nanoparticles, a layer of evenly distributed black particles with a thickness of about 2.59 nm is loaded on the surface of Co3O4, which further indicates that the Ru nanoparticles are successfully deposited on the surface of the ultra-thin two-dimensional nanosheet structure of Co3O4.

[0034] like Figure 4 As shown in Figure 1, the 8-Ru / Co3O4 catalyst prepared in Example 1 is the optimal catalyst. Under low-intensity sunlight (11.9 suns), medium temperature (310°C) and low pressure of 0.5 MPa, the CH4 and CO production rates can reach 32.15 mmol˙g, respectively. -1 ˙h -1 and 0.26mmol˙g -1 ˙h -1The selectivity of CH4 generation is as high as 99.2%. It can be seen that the ultra-thin 8-Ru / Co3O4 catalyst shows extremely high activity and selectivity for CO2 photothermal hydrogenation to produce CH4.

[0035] Figure 5 The surface temperature of the 8-Ru / Co3O4 catalyst under full spectrum light irradiation is shown. When irradiated with full spectrum light, the surface temperature of the 8-Ru / Co3O4 catalyst is stabilized at 310°C, which indicates that the catalyst of the present invention has excellent photothermal conversion ability.

[0036] The Co3O4 used as a carrier in the ultrathin Ru / Co3O4 catalyst is an ultrathin two-dimensional nanosheet structure with Ru nanoparticles uniformly loaded on its surface. The high specific surface area of ​​Ru / Co3O4 provides abundant active sites, especially its naturally prone to forming oxygen vacancies and surface defects, which not only enhance the adsorption and activation of CO2 but also serve as anchoring points to firmly load the Ru nanoparticles, effectively preventing them from agglomerating or losing during high-temperature photothermal reactions, maintaining efficient catalytic activity and good thermal stability. The interface between Ru and Co3O4 in the ultrathin Ru / Co3O4 catalyst promotes the synergistic occurrence of H2 dissociation and CO2 adsorption and activation under photothermal action. Under low-intensity solar illumination (11.9 suns), moderate temperature (310°C) and low pressure of 0.5 MPa, a catalytic efficiency of 32.15 mmol˙g can still be achieved. -1 ˙h -1 The CH4 yield is high, showing its excellent performance under strong solar-driven environment, which is more suitable for actual solar thermochemical conversion scenarios, significantly improving the photothermal catalytic CO2 hydrogenation activity, achieving efficient CO2 conversion, and solving the problem of low activity of existing catalysts.

[0037] Compared with one-dimensional structures such as nanotubes and nanorods, ultrathin two-dimensional nanosheet structures exhibit more significant advantages in photothermal catalytic reactions. First, nanosheets have a larger specific surface area and higher surface exposure, which is conducive to more dispersed loading of active metals (such as Ru) on their surface, thereby forming more active sites accessible to reactants. Second, nanosheet structures are more suitable for constructing two-dimensional interfacial heterojunctions, which is conducive to forming a tighter interfacial synergistic zone between Ru and the support, thereby effectively promoting electron transfer and intermediate stabilization, thereby improving the efficiency of photothermal synergistic catalysis. One-dimensional nanorods or nanotubes are usually arranged linearly. Although they have strong longitudinal mass transfer capabilities, they have certain limitations in constructing high-density surface interfaces and increasing light absorption area. In addition, nanosheet structures have better thermal responsiveness in photothermal conversion. Because their thin layer structure can more efficiently absorb and quickly conduct light energy to form a localized thermal field, they are particularly suitable for enhancing heat-driven reaction processes. Therefore, the selection of ultrathin two-dimensional nanosheet structures is a key structural strategy for achieving efficient photothermal CO2 hydrogenation, which is superior to one-dimensional nanostructures in interface construction and energy coupling.

[0038] It lays the foundation for industrial application. In terms of reaction selectivity, the catalyst can accurately control the product distribution, improve the generation efficiency of high value-added products, reduce by-products, reduce the energy consumption and cost of separation and purification, and improve the overall economic benefits. During the preparation process, by optimizing the preparation process (precisely controlling parameters such as the heating rate, calcination temperature and time), and combining the Ru doping strategy, it effectively prevents the loss of active components and structural collapse, improves the stability of the catalyst, and reduces production costs and process complexity. The catalyst of the present invention is obtained by precipitation method, the process is simple, the operation is convenient, the required raw materials are inexpensive, and it has the potential for long-term recycling and industrial application. It overcomes the limitations of single photocatalysis and pure thermal catalysis, has the advantages of high efficiency, low energy consumption, and recyclability, and is in line with the sustainable development energy strategy. In the photothermal catalytic CO2 hydrogenation reaction, the catalyst usage is small and can be recycled for a long time. It has broad application prospects in the field of CO2 conversion and is suitable for large-scale production.

[0039] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. An ultrathin Ru / Co3O4 catalyst, characterized in that: The Co3O4 used as a carrier in the ultrathin Ru / Co3O4 catalyst is an ultrathin two-dimensional nanosheet structure, and Ru nanoparticles are uniformly loaded on its surface.

2. A method for preparing the ultrathin Ru / Co3O4 catalyst according to claim 1, characterized in that: The steps include: S10, synthesis of ultrathin two-dimensional nanosheet structured Co3O4; S20, dispersing Co3O4 in a mixture of deionized water and methanol to obtain a suspension; S30. Under a nitrogen atmosphere, ruthenium trichloride is added to the suspension, and the mixture is irradiated with a xenon lamp to finally obtain an ultrathin Ru / Co3O4 catalyst.

3. The preparation method according to claim 2, characterized in that The mass of Co3O4 in S30 is 0.01g~10g, and the mass of ruthenium trichloride is 0.001g~0.1g.

4. The preparation method according to claim 2 or 3, characterized in that The irradiation power of the xenon lamp is 10W to 500W. The mixture is stirred during the process of being irradiated with the xenon lamp, and the stirring time is 0.1h to 12h.

5. The preparation method according to any one of claims 2 to 4, characterized in that The synthesis method of Co3O4 is as follows: S11, dissolving the cobalt salt and the surfactant into the aqueous solution and mixing them uniformly; S12, adding sodium borohydride as a reducing agent, dissolving and mixing uniformly, and washing and vacuum drying the resulting precipitate; S13. calcining the precipitate and naturally cooling it to room temperature to obtain Co3O4.

6. The preparation method according to claim 5, characterized in that The cobalt salt is a cobalt-containing soluble salt or a hydrate thereof, the cobalt-containing soluble salt or the hydrate thereof is cobalt nitrate or cobalt chloride, the surfactant is a cationic surfactant, and the cationic surfactant is hexadecyltrimethylammonium bromide.

7. The preparation method according to claim 5, characterized in that The heating rate during the calcination process is 1°C / min to 5°C / min, the calcination temperature is 200°C to 500°C, and the calcination time is 1h to 6h.

8. The preparation method according to claim 7, characterized in that The heating rate during the calcination process is 2°C / min, the calcination temperature is 400°C, and the calcination time is 4h.

9. Use of the ultrathin Ru / Co3O4 catalyst according to claim 1 or the ultrathin Ru / Co3O4 catalyst prepared by the preparation method according to any one of claims 2 to 8, characterized in that: Ultrathin Ru / Co3O4 catalyst is used in photothermal CO2 hydrogenation.

10. The use according to claim 9, characterized in that The ultra-thin Ru / Co3O4 catalyst for CO2 photothermal catalytic conversion specifically includes: The ultra-thin Ru / Co3O4 catalyst is dispersed in a sealed reaction vessel, and deionized water is added. The reaction vessel is then evacuated, and a mixed gas of CO2 and H2 is introduced. A xenon lamp is used as a full-spectrum light source for photothermal catalytic conversion of CO2.

Images