Low-temperature high-activity supported Ru-based catalyst as well as preparation method and application thereof

Abstract

The invention provides a low-temperature high-activity supported Ru-based catalyst as well as a preparation method and application thereof, according to the method, a manganese oxide carrier is synthesized by a precipitation method, and the manganese oxide carrier is supported by a deposition-precipitation method to obtain the supported Ru-based catalyst. By optimizing the synergistic effect of the MnO carrier and the Ru active component, under the conditions of low temperature of 180 DEG C and high space velocity of 36000 mL.g <-1 >. H <-1 >, the CO2 conversion rate as high as 94.9% and the selectivity of 100% are realized, and the bottleneck of insufficient low-temperature activity of the existing catalyst is broken through; meanwhile, the catalyst shows excellent long-term stability, after continuous operation for 100 hours at 180 DEG C, the CO2 conversion rate attenuation is less than 0.5%, the selectivity is always kept at 100%, and a solid durability foundation is laid for industrial application.

Description

Technical Field

[0001] This invention belongs to the field of CO2 catalytic conversion technology, and specifically relates to a low-temperature, high-activity supported Ru-based catalyst, its preparation method, and its application. Background Technology

[0002] CO2 methanation reaction ( Methanation is a strongly exothermic reaction, and low temperature and high pressure favor its progress, but high temperatures produce the byproduct CO. Therefore, conducting the methanation reaction at relatively low temperatures is beneficial for improving methane yield and catalyst durability. However, from a kinetic perspective, due to the high chemical stability of CO2 molecules, the kinetic barrier for their activation hydrogenation to methane is very high. Therefore, developing highly active methanation catalysts at low temperatures remains a significant challenge.

[0003] Ru-based catalysts are currently considered to have the highest catalytic activity in CO2 methanation, especially at low temperatures. Furthermore, due to their high physicochemical stability and lower cost compared to other precious metals, they are among the most suitable active metals for CO2 methanation. The choice of support often determines the particle size of the active metal Ru and the CO2 adsorption sites on the catalyst.

[0004] Therefore, how to select and design the carrier remains a major challenge. Summary of the Invention

[0005] In view of the above, the main objective of this invention is to provide a low-temperature, high-activity supported Ru-based catalyst, its preparation method, and its application, in order to solve the aforementioned technical problems.

[0006] This invention proposes a low-temperature, high-activity supported Ru-based catalyst, which is composed of a manganese oxide support and a Ru main catalyst; Manganese oxide support was synthesized from manganese acetate tetrahydrate by precipitation method, and the manganese oxide support was loaded by deposition precipitation method to obtain supported Ru-based catalyst.

[0007] This invention proposes a method for preparing a low-temperature, high-activity supported Ru-based catalyst, which is used to prepare the above-mentioned supported Ru-based catalyst. The method includes the following steps: Step 1: Place manganese acetate tetrahydrate into beaker A, add deionized water to the beaker and stir to dissolve, to obtain solution A; Step 2: Pour ammonia into beaker B to obtain solution B. Slowly add solution B dropwise to beaker A and stir continuously to obtain a precipitate. Filter and wash the precipitate with deionized water to obtain a washed filter cake. Place the washed filter cake in a constant temperature drying oven for drying. After drying, grind it evenly to obtain manganese oxide carrier. Step 3: Dissolve solid ruthenium chloride in deionized water to form a homogeneous solution; Step 4: Sonicate the homogeneous solution. After sonication, take out the standard solution and put it into beaker C. Add deionized water to dilute it, then add manganese support and stir. After stirring, add ammonia water and continue stirring to obtain the stirred mixture. Step 5: Centrifuge and wash the stirred material, then place it in a constant temperature drying oven to dry it and obtain a dried sample. Grind the dried sample evenly to obtain a fresh catalyst. Perform reduction catalysis on the fresh catalyst under a reducing atmosphere to obtain a supported Ru-based catalyst. The present invention also proposes an application of a low-temperature, high-activity supported Ru-based catalyst. The supported Ru-based catalyst prepared by the above-mentioned method for preparing a low-temperature, high-activity supported Ru-based catalyst is applied to a low-temperature CO2 methanation reaction.

[0008] Beneficial effects: 1. This invention optimizes the synergistic effect between the MnO support and the Ru active component at a low temperature of 180℃ and a concentration of 36000 mL·g. -1 ·h -1 Under high airspeed conditions, a CO2 conversion rate of up to 94.9% and 100% efficiency were achieved. This catalyst exhibits selectivity, overcoming the bottleneck of insufficient low-temperature activity in existing catalysts. Simultaneously, it demonstrates excellent long-term stability, with CO2 conversion rate degradation of less than 0.5% after 100 hours of continuous operation at 180℃. The selectivity remains at 100%, laying a solid foundation for durability for industrial applications.

[0009] 2. This invention, through precise process control, significantly reduces the Ru loading to 5.85 wt.%, which is more than 60% lower than the Ru loading of existing Ru-based CO2 methanation catalysts with excellent low-temperature performance (typically requiring more than 20 wt.%), thus greatly reducing raw material costs. At the same time, the precipitation method used in this invention does not require any high-temperature calcination steps, only conventional drying and low-temperature reduction, which significantly reduces energy consumption, simplifies the process, improves process repeatability and controllability, and reduces equipment requirements, thus possessing excellent industrial scale-up potential and economic feasibility.

[0010] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by means of embodiments of the invention. Attached Figure Description

[0011] Figure 1 The graph shows the CO2 methanation activity results tested in Example 2 and Comparative Examples 1-4.

[0012] Figure 2 This is a comparison of the reaction temperature and CH4 generation rate between Example 2 and existing CO2 methanation catalysts.

[0013] Figure 3 This is a comparison chart of the CO2 methane reaction activity of Example 2 and the current classic and mainstream Ru-based catalysts.

[0014] Figure 4 This is a graph showing the comparison of the catalyst CO2 and methane activity between Example 2 and Comparative Example 7 after high-temperature calcination.

[0015] Figure 5 This is a graph showing the stability test results of Example 2 at 170℃ and 180℃ for 100 hours.

[0016] Figure 6 These are the in-situ X-ray diffraction (XRD) patterns of the precursor from Example 2 treated under different temperatures and atmospheres.

[0017] Figure 7 This is a high-angle annular dark-field scanning transmission electron microscope (HAADF-STEM) image from Example 2.

[0018] Figure 8 This is a graph showing the results of CO2 temperature-programmed desorption (CO2-TPD) in Example 2. Detailed Implementation

[0019] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0020] These and other aspects of the embodiments of the present invention will become clear from the following description and accompanying drawings. In these descriptions and drawings, some specific embodiments of the present invention are specifically disclosed to illustrate some ways of implementing the principles of the embodiments of the present invention; however, it should be understood that the scope of the embodiments of the present invention is not limited thereto.

[0021] Example 1 A low-temperature, high-activity supported Ru-based catalyst, wherein the supported Ru-based catalyst is composed of a manganese oxide support and a Ru main catalyst; Manganese oxide support was synthesized from manganese acetate tetrahydrate by precipitation method, and the manganese oxide support was loaded by deposition precipitation method to obtain supported Ru-based catalyst.

[0022] Example 2 This embodiment provides a method for preparing a low-temperature, high-activity supported Ru-based catalyst, which is used to prepare the aforementioned low-temperature, high-activity supported Ru-based catalyst. The method includes the following steps: Step 1: Take 15g of manganese acetate tetrahydrate and put it into beaker A. Add 80mL of deionized water to the beaker and stir to dissolve for 5min to obtain solution A. Step 2: Pour 20 mL of ammonia water into beaker B to obtain solution B. Slowly add solution B dropwise into beaker A and stir continuously for 3 hours to make the pH of solution B 10, thus obtaining a precipitate. Filter and wash the precipitate three times with deionized water to obtain a washed filter cake. Place the washed filter cake in a constant temperature drying oven at 100℃ for 4 hours. After drying, grind it evenly to obtain manganese oxide carrier. Step 3: Dissolve 2.57g of ruthenium chloride solid in 100mL of deionized water to form a homogeneous solution; Step 4: Sonicate the homogeneous solution. After sonication, take out 7 mL of standard solution and put it into beaker C. Add 15 mL of deionized water to dilute it. Then add 0.93 g of manganese carrier and stir. After stirring, add 20 mL of ammonia water and continue stirring until the pH of the solution is 10 to obtain the stirred material. Step 5: Centrifuge and wash the stirred material 4 times, then place it in a 100℃ constant temperature drying oven for 4 hours to obtain a dried sample. Grind the dried sample evenly to obtain a fresh catalyst (precursor of Example 2). Reduce the fresh catalyst in a 9:1 argon and hydrogen mixed atmosphere at 200℃ and a flow rate of 25 mL / min for 1.5 hours to obtain a supported Ru-based catalyst, denoted as Al.

[0023] Example 3 This embodiment provides a method for preparing a low-temperature, high-activity supported Ru-based catalyst, which is used to prepare the aforementioned low-temperature, high-activity supported Ru-based catalyst. The method includes the following steps: Step 1: Take 15.5g of manganese acetate tetrahydrate and put it into beaker A. Add 100mL of deionized water to the beaker and stir to dissolve for 15min to obtain solution A. Step 2: Pour 30 mL of ammonia water into beaker B to obtain solution B. Slowly add solution B dropwise into beaker A and stir continuously for 4.5 h to make the pH of solution B 10, and obtain a precipitate. Filter and wash the precipitate with deionized water 4 times to obtain a washed filter cake. Place the washed filter cake in a constant temperature drying oven at 100℃ for 5 h. After drying, grind it evenly to obtain manganese oxide carrier. Step 3: Dissolve 2.5-7.5g of ruthenium chloride solid in 100mL of deionized water to form a homogeneous solution; Step 4: Sonicate the homogeneous solution. After sonication, take out 7 mL of standard solution and put it into beaker C. Add 20 mL of deionized water to dilute it. Then add 0.93 g of manganese carrier and stir. After stirring, add 30 mL of ammonia water and continue stirring until the pH of the solution is 10 to obtain the stirred material. Step 5: Centrifuge and wash the stirred material 5 times, then place it in a 100℃ constant temperature drying oven for 5 hours to obtain the dried sample. Grind the dried sample evenly to obtain a fresh catalyst (precursor of Example 3). Reduce and catalyze the fresh catalyst in a 9:1 argon and hydrogen mixed atmosphere at 225℃ and a flow rate of 30 mL / min for 2 hours to obtain a supported Ru-based catalyst, denoted as A2.

[0024] Example 4 This embodiment provides a method for preparing a low-temperature, high-activity supported Ru-based catalyst, which is used to prepare the aforementioned low-temperature, high-activity supported Ru-based catalyst. The method includes the following steps: Step 1: Take 16g of manganese acetate tetrahydrate and put it into beaker A. Add 100mL of deionized water to the beaker and stir to dissolve for 30min to obtain solution A. Step 2: Pour 40 mL of ammonia water into beaker B to obtain solution B. Slowly add solution B dropwise into beaker A and stir continuously for 6 hours to make the pH of solution B 10, thus obtaining a precipitate. Filter and wash the precipitate 5 times with deionized water to obtain a washed filter cake. Place the washed filter cake in a constant temperature drying oven at 100℃ for 6 hours. After drying, grind it evenly to obtain manganese oxide carrier. Step 3: Dissolve 2.58g of ruthenium chloride solid in 100mL of deionized water to form a homogeneous solution; Step 4: Sonicate the homogeneous solution. After sonication, take out 7 mL of standard solution and put it into beaker C. Add 25 mL of deionized water to dilute it. Then add 0.93 g of manganese support and stir. After stirring, add 40 mL of ammonia water and continue stirring until the pH of the solution is 10 to obtain the stirred material. Step 5: Centrifuge and wash the stirred material 6 times, then place it in a 100℃ constant temperature drying oven for 6 hours to obtain a dried sample. Grind the dried sample evenly to obtain a fresh catalyst (precursor of Example 4). Reduce the fresh catalyst in a 9:1 argon and hydrogen mixed atmosphere at 250℃ and a flow rate of 35 mL / min for 2.5 hours to obtain a supported Ru-based catalyst, denoted as A3.

[0025] Comparative Example 1 The difference between Comparative Example 1 and Example 2 is that some parameters have been changed, and the method includes the following steps: Step 1: Take 15g of manganese acetate tetrahydrate and put it into beaker A. Add 80mL of deionized water to the beaker and stir to dissolve for 5min to obtain solution A. Step 2: Pour 20 mL of ammonia water into beaker B to obtain solution B. Slowly add solution B dropwise into beaker A and stir continuously for 3 hours to make the pH of solution B 10, thus obtaining a precipitate. Filter and wash the precipitate three times with deionized water to obtain a washed filter cake. Place the washed filter cake in a constant temperature drying oven at 100℃ for 4 hours. After drying, grind it evenly to obtain manganese oxide carrier. Step 3: Dissolve 2.57g of ruthenium chloride solid in 100mL of deionized water to form a homogeneous solution; Step 4: Sonicate the homogeneous solution for 3 min. After sonication, take out 1 mL of standard solution and dilute it with 15 mL of deionized water. After dilution, add 0.99 g of manganese oxide carrier and stir for 3 h. After stirring, add 20 mL of ammonia water until the pH is 10 and continue stirring for 4 h to obtain the stirred material. Step 5: Centrifuge the stirred material and wash it with ultrapure water. Then dry it in a constant temperature drying oven at 100℃ for 6 hours to obtain the dried sample. Grind the dried sample evenly to obtain the precursor of Comparative Example 1. Reduce the precursor of Comparative Example 1 at 250℃ for 2 hours in an Ar atmosphere with a volume fraction of 10% H2 / 90% to obtain the supported Ru-based catalyst, denoted as B1.

[0026] Comparative Example 2 The difference between Comparative Example 2 and Example 2 is that some parameters have been changed, and the method includes the following steps: Step 1: Take 15g of manganese acetate tetrahydrate and put it into beaker A. Add 80mL of deionized water to the beaker and stir to dissolve for 5min to obtain solution A. Step 2: Pour 20 mL of ammonia water into beaker B to obtain solution B. Slowly add solution B dropwise into beaker A and stir continuously for 3 hours to make the pH of solution B 10, thus obtaining a precipitate. Filter and wash the precipitate three times with deionized water to obtain a washed filter cake. Place the washed filter cake in a constant temperature drying oven at 100℃ for 4 hours. After drying, grind it evenly to obtain manganese oxide carrier. Step 3: Dissolve 2.57g of ruthenium chloride solid in 100mL of deionized water to form a homogeneous solution; Step 4: Sonicate the homogeneous solution for 3 min. After sonication, take out 3 mL of standard solution and dilute it with 15 mL of deionized water. After dilution, add 0.97 g of manganese oxide carrier and stir for 3 h. After stirring, add 20 mL of ammonia water until the pH is 10 and continue stirring for 4 h to obtain the stirred material. Step 5: Centrifuge the stirred material and wash it with ultrapure water. Then, dry it in a constant temperature drying oven at 100℃ for 6 hours to obtain the dried sample. Grind the dried sample evenly to obtain the precursor of Comparative Example 2. Reduce the precursor of Comparative Example 2 at 250℃ for 2 hours in an Ar atmosphere with a volume fraction of 10% H2 / 90% to obtain the supported Ru-based catalyst, denoted as B2.

[0027] Comparative Example 3 The difference between Comparative Example 3 and Example 2 is that some parameters have been changed, and the method includes the following steps: Step 1: Take 15g of manganese acetate tetrahydrate and put it into beaker A. Add 80mL of deionized water to the beaker and stir to dissolve for 5min to obtain solution A. Step 2: Pour 20 mL of ammonia water into beaker B to obtain solution B. Slowly add solution B dropwise into beaker A and stir continuously for 3 hours to make the pH of solution B 10, thus obtaining a precipitate. Filter and wash the precipitate three times with deionized water to obtain a washed filter cake. Place the washed filter cake in a constant temperature drying oven at 100℃ for 4 hours. After drying, grind it evenly to obtain manganese oxide carrier. Step 3: Dissolve 2.57g of ruthenium chloride solid in 100mL of deionized water to form a homogeneous solution; Step 4: Sonicate the homogeneous solution for 3 min. After sonication, take out 5 mL of standard solution and dilute it with 15 mL of deionized water. After dilution, add 0.95 g of manganese oxide carrier and stir for 3 h. After stirring, add 20 mL of ammonia water until the pH is 10 and continue stirring for 4 h to obtain the stirred product. Step 5: Centrifuge the stirred material and wash it with ultrapure water. Then, dry it in a constant temperature drying oven at 100℃ for 6 hours to obtain the dried sample. Grind the dried sample evenly to obtain the precursor of Comparative Example 3. Reduce the precursor of Comparative Example 3 at 250℃ for 2 hours in an Ar atmosphere with a volume fraction of 10% H2 / 90% to obtain the supported Ru-based catalyst, denoted as B3.

[0028] Comparative Example 4 The difference between Comparative Example 4 and Example 2 is that some parameters have been changed, and the method includes the following steps: Step 1: Take 15g of manganese acetate tetrahydrate and put it into beaker A. Add 80mL of deionized water to the beaker and stir to dissolve for 5min to obtain solution A. Step 2: Pour 20 mL of ammonia water into beaker B to obtain solution B. Slowly add solution B dropwise into beaker A and stir continuously for 3 hours to make the pH of solution B 10, thus obtaining a precipitate. Filter and wash the precipitate three times with deionized water to obtain a washed filter cake. Place the washed filter cake in a constant temperature drying oven at 100℃ for 4 hours. After drying, grind it evenly to obtain manganese oxide carrier. Step 3: Dissolve 2.57g of ruthenium chloride solid in 100mL of deionized water to form a homogeneous solution; Step 4: Sonicate the homogeneous solution for 3 min. After sonication, take out 9 mL of standard solution and dilute it with 15 mL of deionized water. After dilution, add 0.91 g of manganese oxide carrier and stir for 3 h. After stirring, add 20 mL of ammonia water until the pH is 10 and continue stirring for 4 h to obtain the stirred material. Step 5: Centrifuge the stirred material and wash it with ultrapure water. Then, dry it in a constant temperature drying oven at 100℃ for 6 hours to obtain the dried sample. Grind the dried sample evenly to obtain the precursor of Comparative Example 4. Reduce the precursor of Comparative Example 4 at 250℃ for 2 hours in an Ar atmosphere with a volume fraction of 10% H2 / 90% to obtain the supported Ru-based catalyst, denoted as B4.

[0029] Comparative Example 5 Comparative Example 5 uses anatase TiO2-supported Ru catalyst, and the method includes the following steps: Step 1: Add 10g of tetrabutyl titanate to a beaker, add 30mL of ultrapure water, stir for 15min to obtain a mixture; Step 2: Transfer the mixture to a polytetrafluoroethylene liner and hydrothermally heat it at 100℃ for 24 hours to obtain a hydrothermal solid product. Wash the hydrothermal solid product with ethanol and ultrapure water respectively, and then dry it in a constant temperature drying oven at 110℃ for 6 hours to obtain a dried sample. Grind the dried sample evenly and then place it in a muffle furnace and calcine it at 500℃ for 4 hours with a heating rate of 2℃ / min to obtain anatase TiO2 support. Step 3: Dissolve 2.57g of ruthenium chloride solid in 100mL of deionized water to form a homogeneous solution; Step 4: Sonicate the homogeneous solution for 3 min. After sonication, take out 7 mL of standard solution and dilute it with 15 mL of deionized water. After dilution, add 0.93 g of anatase TiO2 support and stir for 3 h. After stirring, add 20 mL of ammonia water until the pH is 10 and continue stirring for 4 h to obtain the stirred material. Step 5: Centrifuge the stirred material and wash it with ultrapure water. Then, dry it in a constant temperature drying oven at 100℃ for 6 hours to obtain the dried sample. Grind the dried sample evenly to obtain the precursor of Comparative Example 5. Reduce the precursor of Comparative Example 5 at 250℃ for 2 hours in an Ar atmosphere with a volume fraction of 10% H2 / 90% to obtain the supported Ru / TiO2 catalyst, denoted as B5.

[0030] Comparative Example 6 Comparative Example 6 uses a CeO2-supported Ru catalyst, and the method includes the following steps: Step 1: Add 12g of cerium nitrate to a beaker, add 50mL of ultrapure water, stir for 15min to obtain a transparent solution; Step 2: Add ammonia water to precipitate the above transparent solution, adjust the pH to 10 and stir for 3 hours. Wash the precipitate with ultrapure water and then dry it in a constant temperature drying oven at 110℃ for 6 hours to obtain the dried sample. Grind the dried sample evenly and then place it in a muffle furnace and calcine it at 500℃ for 4 hours with a heating rate of 2℃ / min to obtain the CeO2 support. Step 3: Dissolve 2.57g of ruthenium chloride solid in 100mL of deionized water to form a homogeneous solution; Step 4: Sonicate the homogeneous solution for 3 min. After sonication, take out 7 mL of standard solution and dilute it with 15 mL of deionized water. After dilution, add 0.93 g of the above CeO2 carrier and stir for 3 h. After stirring, add 20 mL of ammonia water until the pH is 10 and continue stirring for 4 h to obtain the stirred product. Step 5: Centrifuge the stirred material and wash it with ultrapure water. Then, dry it in a constant temperature drying oven at 100℃ for 6 hours to obtain the dried sample. Grind the dried sample evenly to obtain the precursor of Comparative Example 6. Reduce the precursor of Comparative Example 6 at 250℃ for 2 hours in an Ar atmosphere with a volume fraction of 10% H2 / 90% to obtain the supported Ru / CeO2 catalyst, denoted as B6.

[0031] Comparative Example 7 The difference between Comparative Example 7 and Example 2 is that the catalyst underwent calcination treatment, and the reduction conditions were 250°C for 2 hours. The method included the following steps: Step 1: Take 15g of manganese acetate tetrahydrate and put it into beaker A. Add 80mL of deionized water to the beaker and stir to dissolve for 5min to obtain solution A. Step 2: Pour 20 mL of ammonia water into beaker B to obtain solution B. Slowly add solution B dropwise to beaker A and stir continuously for 3 hours to make the pH of solution B 10, thus obtaining a precipitate. Filter and wash the precipitate three times with deionized water to obtain a washed filter cake. Place the washed filter cake in a constant temperature drying oven at 100℃ for 4 hours. After drying, grind it evenly to obtain a ground sample. Calcine the ground sample at 500℃ for 4 hours to obtain a manganese oxide support (calcination process heating rate 2℃ / min). Step 3: Dissolve 2.57g of ruthenium chloride solid in 100mL of deionized water to form a homogeneous solution; Step 4: Sonicate the homogeneous solution for 3 min. After sonication, take out 7 mL of standard solution and dilute it with 15 mL of deionized water. After dilution, add 0.93 g of the above manganese oxide carrier and stir for 3 h. After stirring, add 20 mL of ammonia water until the pH is 10 and continue stirring for 4 h to obtain the stirred material. Step 5: Centrifuge the stirred material and wash it with ultrapure water. Then, dry it in a constant temperature drying oven at 100℃ for 6 hours to obtain the dried sample. Grind the dried sample evenly to obtain the ground sample. Calcine the ground sample at 500℃ for 4 hours to obtain the precursor of Comparative Example 7. Reduce the precursor of Comparative Example 7 at 250℃ for 2 hours under an Ar atmosphere with a volume fraction of 10% H2 / 90% to obtain the supported Ru-based catalyst, denoted as B7.

[0032] Application Example 1 An application of a low-temperature, high-activity supported Ru-based catalyst: The supported Ru-based catalyst prepared using the above-mentioned method for preparing a low-temperature, high-activity supported Ru-based catalyst is applied to a low-temperature catalytic CO2 methanation reaction, specifically including the following steps: The Ru-based catalyst in A1 was loaded into a fixed-bed reactor, and a mixture of 10% argon and 90% hydrogen (H2:Ar = 1:9) was introduced. The reactor was heated to 250°C using a microtube furnace and reduced for 2 hours at a reducing gas flow rate of 30 mL / min. -1 After the temperature of the microtube furnace stabilizes at 160℃, a reaction mixture of 80% hydrogen and 20% carbon dioxide (H2:CO2 = 4:1) is introduced at a flow rate of 60 mL / min. -1 The reaction is carried out at 160-250℃.

[0033] To verify the effectiveness of the present invention, performance tests were conducted on Example 2 and Comparative Examples 1-4. The test method is as follows: Catalytic activity was evaluated using a GC9790Ⅱ gas chromatograph from Zhejiang Fuli Analytical Instrument Co., Ltd. The reaction gas was a mixture of 20% CO2 and 80% H2 (CO2:H2=1:4), and the reducing gas was a mixture of 10% H2 / 90% Ar. 0.1g of catalyst and 0.1g of quartz sand were weighed, mixed uniformly, and loaded into a fixed-bed straight reaction tube. The mixture was pretreated and reduced at 250℃ for 2 hours under reducing gas at a flow rate of 30mL·min. -1 After cooling to 160℃, the reducing gas is switched to the reactant gas at a flow rate of 60 mL / min. -1 The test temperature was 160℃-250 / 350℃. The reaction tail gas was analyzed online by gas chromatography, using pure argon as the carrier gas. After separation by the chromatographic column, the gas was detected by a TCD detector.

[0034] In Examples 2 and Comparative Examples 1-4, the same manganese oxide support was used, but the Ru loading of the catalysts with different activities was measured by inductively coupled plasma optical emission spectrometry (ICP-OES) as shown in Table 1. The Ru loadings of Examples 2, Comparative Examples 1, 2, 3 and 4 were 5.85 wt.%, 0.76 wt.%, 2.41 wt.%, 4.30 wt.% and 7.37 wt.%, respectively.

[0035] Table 1: Ru loading measured by ICP-OES

[0036] The CO2 methanation reactivity test results of Example 2 and Comparative Examples 1, 2, 3 and 4 are as follows: Figure 1 As shown, the Ru loading significantly affects the reactivity. For Comparative Example 1 with a low Ru loading (0.76 wt.%), an 80% CO2 conversion rate needs to be achieved at a high temperature of 300°C. As the Ru loading increases to 5.85 wt.%, Example 2 exhibits the highest low-temperature reactivity, achieving an ultra-high CO2 conversion rate of 94.9% at a low temperature of 180°C, close to the thermal equilibrium curve at this temperature. Furthermore, Example 2 achieves 100% CO2 conversion rate throughout the entire test temperature range (160-250°C). Selectivity. These results demonstrate the unique competitive advantage of Example 2 in terms of activity, solving the problem of insufficient low-temperature activity of current CO2 methanation catalysts.

[0037] Figure 2 Example 2 was compared with existing CO2 methanation catalysts (Ru). x Ti y O z RuO x C y @C、CeZrOx The reaction temperature of Ni / CeO2-R and the corresponding CH4 formation rate. Example 2: at 180°C The formation rate is 84.7 μmol·g -1 ·s -1 At this temperature, Ru x Ti y O z and RuO x C y The CH4 formation rates of the @C catalyst were 38.6 and 30.6 μmol·g, respectively. -1 ·s -1 The reactivity of Example 2 is more than 50% lower than that of Example 2. These results confirm that the reactivity of Example 2 is significantly higher than that of existing catalysts, and Example 2 exhibits better performance at a lower temperature of 180°C. The generation rate is significantly higher than that of existing catalysts, which demonstrates the unique competitive advantage of Example 2 in terms of activity and effectively solves the problem of insufficient low-temperature activity of current CO2 methanation catalysts.

[0038] Figure 3 Example 2 compares its reactivity with that of current classic low-temperature CO2 methanation Ru-based catalysts. Example 2 has the same theoretical Ru loading as Comparative Example 5 (Ru / TiO2) and Comparative Example 6 (Ru / CeO2). Comparative Example 5 achieves a CO2 conversion of 86.4% at 220°C, and Comparative Example 6 achieves a CO2 conversion of 94.2% at 210°C, with significantly lower reactivity than Example 2 (94.9% CO2 conversion at 180°C). These differences in activity stem from the significantly superior synergistic effect between the MnO support and Ru during the reaction compared to the current mainstream supports TiO2 and CeO2.

[0039] Figure 4 The comparison of the CO2 methanation activity between the uncalcined catalyst of Example 2 and the catalyst of Comparative Example 7 calcined at 500°C shows that after high-temperature calcination, Comparative Example 7 requires 230°C to achieve a CO2 conversion rate of 71.6%, which is 50°C higher than that of Example 2. This indicates that high-temperature calcination has a significant inhibitory effect on catalyst activity. This highlights that the catalyst synthesized without a calcination step proposed in this invention has much higher reactivity than the catalyst calcined at high temperatures. On the other hand, the elimination of calcination in the synthesis process saves on catalyst preparation costs. These results demonstrate the competitive advantages of this invention.

[0040] The change in CO2 conversion rate under long-term stable operation in Example 2 was further tested, such as... Figure 5As shown in the figure, this embodiment first operated stably at 180℃ for 20 hours, maintaining a CO2 conversion rate of 94.1%. Then, the temperature was lowered to 170℃, causing the CO2 conversion rate to decrease to 15% and stabilize for 10 hours. Next, the temperature was raised to 180℃ and maintained for 70 hours, during which the CO2 conversion rate decreased from the initial 94.1% to a final 93.6%, a decrease of no more than 0.5%. The selectivity remained at 100%, indicating that this embodiment has good stability under high and low CO2 conversion cycle tests, demonstrating its excellent prospects for industrial application.

[0041] Figure 6 In-situ XRD patterns of the precursor of Example 2 under different conditions were tested. The precursor of Example 2 exhibited characteristic diffraction peaks of Mn3O4 at room temperature. After in-situ reduction at 250°C in a 10% H2 / 90% Ar atmosphere for 30 min, Mn3O4 was reduced to MnO. Even after passing a slightly diluted reaction gas (10% CO2 / 40% H2 / 50% Ar) at the same temperature for 30 min, the MnO structure remained unchanged, indicating that Example 2 was in the MnO crystalline phase under the reaction conditions. Furthermore, no characteristic diffraction peaks of Ru were detected, indicating that Ru was highly dispersed on the surface of the MnO support.

[0042] Example 2: The average Ru particle size obtained by HAADF-STEM testing is as follows: Figure 7 As shown, the brighter particles are Ru with a larger atomic number and are uniformly distributed; the average particle size of Ru was only 2.34 ± 0.56 nm, indicating that the Ru in Example 2 is well dispersed on the MnO support. Figure 6 In-situ XRD spectrum Figure 1 To.

[0043] Figure 8 The CO2-TPD results for Example 2 and its carrier are shown below. In Example 2, a small amount of CO2 desorption mass spectrometry signal was detected at 168°C (mass spectrometry detection molecule nucleus-to-mass ratio was 4:4), and the quantified desorption amount was 0.07 μmol·g. -1 This indicates that only a small number of weakly basic sites exist on the surface of the carrier in Example 2; for Example 2, a large amount of CO2 desorption signals were detected at 95°C, 168°C, 336°C, and 509°C, with a total desorption amount of 1.17 μmol·g. -1 The concentration of CO2 in the carrier of Example 2 is 17 times that of the carrier of Example 2, indicating that the surface of Example 2 has an extremely rich number of weakly basic and moderately basic sites, far exceeding that of its carrier. This is due to the synergistic effect of the interface between the active Ru and the MnO carrier, which greatly promotes the adsorption of CO2. This is the key factor for the excellent low-temperature activity of Example 2.

[0044] In summary, this invention creatively proposes a supported Ru-based catalyst with manganese oxide (MnO) as the support and ruthenium (Ru) as the main active component, along with its preparation method. This represents a breakthrough in solving the core technical challenge of low-temperature, high-activity CO2 methanation. Its core innovation lies in: the use of a synergistic Ru and MnO strategy to prepare a record-breaking low-temperature, high-activity CO2 methanation catalyst, far exceeding current mainstream catalysts, exhibiting excellent selectivity and long-term stable operation; compared to current Ru-based catalysts with superior low-temperature activity, it significantly reduces the amount of precious metal Ru used, significantly lowering catalyst costs and improving economic feasibility; the process of this invention is simple, reproducible, easy to control, and requires minimal equipment (only conventional precipitation and deposition, drying, without any high-temperature calcination), possessing excellent potential for industrial scale-up and significant application value and broad market prospects in the field of CO2 resource utilization.

[0045] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0046] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for preparing a low-temperature, high-activity supported Ru-based catalyst, characterized in that, The method includes the following steps: Step 1: Place manganese acetate tetrahydrate into beaker A, add deionized water to the beaker and stir to dissolve, to obtain solution A; Step 2: Pour ammonia into beaker B to obtain solution B. Slowly add solution B dropwise to beaker A while stirring continuously to obtain a precipitate. Filter and wash the precipitate with deionized water to obtain a washed filter cake. Place the washed filter cake in a constant temperature drying oven for drying. After drying, grind it evenly to obtain a manganese oxide carrier. Step 3: Dissolve solid ruthenium chloride in deionized water to form a homogeneous solution; Step 4: Sonicate the homogeneous solution. After sonication, take out the standard solution and put it into beaker C. Add deionized water to dilute it, then add manganese oxide carrier and stir. After stirring, add ammonia water and continue stirring to obtain the stirred mixture. Step 5: Centrifuge and wash the stirred material, then place it in a constant temperature drying oven to dry it and obtain a dried sample. Grind the dried sample evenly to obtain a fresh catalyst. Perform reduction catalysis on the fresh catalyst under a reducing atmosphere to obtain a supported Ru-based catalyst. The reducing atmosphere is a mixture of argon and hydrogen in a ratio of 9:

1.

2. The method for preparing a low-temperature, high-activity supported Ru-based catalyst according to claim 1, characterized in that, In the process of obtaining solution A, the mass of manganese acetate tetrahydrate is 15-16g, the volume of deionized water added is 80-120mL, and the stirring and dissolving time is 5-30min.

3. The method for preparing a low-temperature, high-activity supported Ru-based catalyst according to claim 1, characterized in that, In the process of obtaining manganese oxide support, the volume of ammonia water added is 20-40 mL. The solution B is slowly added dropwise to beaker A and stirred for 3-6 hours. The pH value of the solution after stirring is 10. The solution is filtered and washed with deionized water 3-5 times. The temperature of the constant temperature drying oven is 100℃ and the drying time is 4-6 hours.

4. The method for preparing a low-temperature, high-activity supported Ru-based catalyst according to claim 1, characterized in that, During the formation of a homogeneous solution, the mass of ruthenium chloride solid is 2.57-2.58 g, and the volume dissolved in deionized water is 100 mL.

5. The method for preparing a low-temperature, high-activity supported Ru-based catalyst according to claim 1, characterized in that, During the process of obtaining the stirred mixture, the volume of standard solution taken out is 7 mL, the volume of deionized water added is 15-25 mL, the mass of manganese oxide carrier added is 0.93 g, the stirring time is 3 h, and the volume of ammonia water added after stirring is 20-40 mL.

6. The method for preparing a low-temperature, high-activity supported Ru-based catalyst according to claim 1, characterized in that, In the process of obtaining the supported Ru-based catalyst, the number of centrifugal washings is 4-6 times, the temperature of the constant temperature drying oven is 100℃, and the drying time in the constant temperature drying oven is 4-6h; the flow rate of the reducing atmosphere is 25-35mL / min, the reduction temperature of the reducing atmosphere is 200-250℃, and the reduction time is 1.5-2.5h.

7. A low-temperature, high-activity supported Ru-based catalyst, wherein the supported Ru-based catalyst is prepared by the preparation method of the low-temperature, high-activity supported Ru-based catalyst according to any one of claims 1 to 6.

8. The low-temperature, high-activity supported Ru-based catalyst according to claim 7, characterized in that, The supported Ru-based catalyst has a Ru loading of 5.85 wt.% and an average Ru particle size of 2.34 ± 0.56 nm. The supported Ru-based catalyst has a CO2 conversion rate of 94.9% at a low temperature of 180 °C and a CH4 selectivity of 100% in the range of 160-250 °C.

9. The application of a low-temperature, high-activity supported Ru-based catalyst, employing the supported Ru-based catalyst according to claim 7, characterized in that, The supported Ru-based catalyst is used in a low-temperature CO2 methanation reaction.

10. The application of the low-temperature, high-activity supported Ru-based catalyst according to claim 9, characterized in that, In the low-temperature CO2 methanation reaction, the supported Ru-based catalyst exhibits a CH4 formation rate of 84.7 μmol·g at 180 °C. -1 ·s -1 .

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