Method for preparing Pt / La2O2CO3 nano-catalyst from La2O2CO3 loaded Pt nano-particles and application of Pt / La2O2CO3 nano-catalyst
By using La2O2CO3 as a support, a Pt/La2O2CO3 nanocatalyst with excellent alkaline surface and anti-sintering properties was prepared, which solved the problem of insufficient stability of Pt-based catalysts at high temperatures in the reverse water-gas shift reaction and achieved efficient CO2 to CO conversion.
Patent Information
- Application Number
- CN202511876863.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-12
- Publication Date
- 2026-05-12
AI Technical Summary
Existing Pt-based catalysts exhibit insufficient stability at high temperatures in reverse water-gas shift reactions, resulting in low CO2 activation efficiency, high energy consumption, and high costs, which limits their industrial application.
Using La2O2CO3 as a support, Pt/La2O2CO3 nanocatalysts were prepared by colloidal deposition. Combined with hydrothermal synthesis and calcination processes, Pt/La2O2CO3 nanocatalysts with excellent alkaline surface and anti-sintering properties were prepared.
The activity, selectivity and stability of the catalyst were improved, the problem of activity and stability of Pt-based catalysts at high temperatures was solved, and the reaction of CO2 to CO with high efficiency was realized.
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Figure CN122006768A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of nanocatalyst preparation technology, and in particular to a method for preparing Pt / La2O2CO3 nanocatalysts by supporting Pt nanoparticles with La2O2CO3 and the application of the catalyst. Background Technology
[0002] Driven by the global energy structure transformation and the "dual carbon" goal, the resource utilization of carbon dioxide (CO2) has become a key breakthrough. Reverse water-gas shift reaction (RWGS: CO2 + H2 → CO + H2O), as a core technology for converting CO2 into high-value-added syngas (CO / H2), has significant strategic value in the chemical, metallurgical, and hydrogen energy fields. However, the high energy consumption of this reaction (endothermic reaction requiring 500-800℃) and the high cost and easy deactivation of precious metal catalysts severely restrict its industrial application. Platinum (Pt)-based catalysts have become a research hotspot for RWGS reactions due to their excellent hydrogenation activity and anti-sintering properties, but their insufficient stability under high-temperature oxidation environments and low CO2 activation efficiency urgently need to be addressed.
[0003] La2O2CO3, as a novel catalyst support, exhibits significant advantages in reactions such as reverse water-gas shift (RWGS). Compared with traditional oxide supports (such as CeO2 and Al2O3), it has the following characteristics: (1) Unique layered structure and enrichment of oxygen vacancies: La2O2CO3 is composed of alternating La2O2 2 ⁺ and CO3 2 The structure consists of ⁻ layers, with a significantly higher concentration of oxygen vacancies between the layers than that of traditional oxides. This structure not only enhances the chemical adsorption capacity of CO2, but also promotes the heterolytic dissociation of H2, forming hindered Lewis acid-base pairs (FLP), thereby accelerating the RWGS reaction rate. In contrast, although CeO2 has oxygen vacancies, it is prone to structural reconstruction at high temperatures, leading to the deactivation of active sites. (2) Excellent alkaline surface and anti-sintering performance: The strong alkaline surface of La2O2CO3 can stabilize carbonate intermediates and reduce the generation of by-products. At the same time, its layered structure can still maintain stability in high-temperature oxidation environments, effectively inhibiting the migration and aggregation of Pt nanoparticles. Traditional Al2O3 supports are prone to sintering at high temperatures, and the surface acidity may lead to catalyst poisoning. (3) Synergistic catalytic effect and industrial adaptability: Pt-loaded La2O2CO3 can achieve high CO selectivity. Its oxygen storage capacity and the alkalinity of the support synergistically optimize the reaction pathway, making it suitable for industrial-grade H2 / CO2 ratio conditions. While composite supports such as Y2O3 / Al2O3 can enhance CO2 adsorption, they require complex modification processes and are costly. Therefore, La2O2CO3, through structural innovation, has overcome the bottlenecks of traditional supports in terms of stability, activity, and cost, providing a new approach for efficient CO2 conversion. Summary of the Invention
[0004] This invention discloses a method for preparing Pt / La2O2CO3 nanocatalysts by supporting Pt nanoparticles in La2O2CO3 and the application of the catalyst. The preparation process of this catalyst is simple, and the catalyst has high activity, selectivity and stability, which solves the problems of low activity and stability of Pt-based catalysts at high temperatures in the catalytic reaction of CO2 hydrogenation to CO.
[0005] To achieve the above objectives, the present invention adopts the following technical solution:
[0006] The method for preparing Pt / La2O2CO3 nanocatalysts by supporting Pt nanoparticles with La2O2CO3, and the preparation of Pt / La2O2CO3-S catalysts, includes the following steps:
[0007] a. Synthesis of La2O2CO3 single carrier La2O2CO3-S
[0008] 1 g of La(NO3)3•6H2O was added to 60 mL of deionized water, and the pH was adjusted to 12 with NaOH while stirring continuously. The stirring was continued for 1 h, and then transferred to a 100 mL hydrothermal synthesis reactor. The mixture was heated at 100-120 °C for 16 h, cooled to room temperature, and filtered through a Buchner funnel to obtain a white precipitate. The precipitate was washed with deionized water, dried at 60-80 °C for 10 h, and ground to obtain a white powder. Finally, the white powder was calcined in a muffle furnace at 400-600 °C for 4 h to obtain a single La2O2CO3 support, denoted as La2O2CO3-S.
[0009] b. Preparation of Pt colloids
[0010] 0.05-0.10 g PtCl4, 0.08-0.12 g NaOH and 20-40 mL ethylene glycol were added sequentially to a 150 mL round-bottom flask. The mixture was stirred at room temperature until homogeneous. Then, while stirring, the mixture was refluxed in an oil bath at 180-200℃ for 2-4 hours to obtain a black Pt colloid.
[0011] c. Preparation of Pt / La2O2CO3-S catalysts with different Pt loadings using colloidal deposition method
[0012] 0.5 g of La2O2CO3-S was dispersed in 25 mL of deionized water and uniformly dispersed by stirring and sonication. Then, a certain amount of Pt colloid was added dropwise at room temperature and stirred continuously for 24 h. Subsequently, the Pt / La2O2CO3-S catalyst was obtained by centrifugation, washing with deionized water, and drying at 80 °C for 10 h.
[0013] Furthermore, it also includes the preparation of the Pt / La2O2CO3-M catalyst, comprising the following processes:
[0014] (1) The process of synthesizing the mixed support La2O3 and La2O2CO3, La2O2CO3-M:
[0015] 1 g of La(NO3)3•6H2O was added to 60 mL of deionized water, and the pH was adjusted to 12 with NaOH while stirring continuously. The stirring was continued for 1 h, and then transferred to a 100 mL hydrothermal synthesis reactor. The mixture was heated at 100-120 °C for 8 h, and after cooling to room temperature, it was filtered through a Buchner funnel to obtain a white precipitate. The precipitate was washed with deionized water and dried at 60-80 °C for 10 h. After grinding, a white powder was obtained. Finally, the white powder was calcined in a muffle furnace at 400-600 °C for 4 h to obtain a carrier of mixed La2O3 and La2O2CO3, denoted as La2O2CO3-M.
[0016] (2) Preparation of Pt colloid
[0017] 0.05-0.10 g PtCl4, 0.08-0.12 g NaOH and 20-40 mL ethylene glycol were added sequentially to a 150 mL round-bottom flask. The mixture was stirred at room temperature until homogeneous. Then, while stirring, the mixture was refluxed in an oil bath at 180-200℃ for 2-4 hours to obtain a black Pt colloid.
[0018] (3) Pt / La2O2CO3-M catalysts with different Pt loadings were prepared by colloidal deposition method.
[0019] 0.5 g of La2O2CO3-M was dispersed in 25 mL of deionized water and uniformly dispersed by stirring and sonication. Then, a certain amount of Pt colloid was added dropwise at room temperature and stirred continuously for 24 h. Subsequently, the Pt / La2O2CO3-M catalyst was obtained by centrifugation, washing with deionized water, and drying at 80 °C for 10 h.
[0020] Furthermore, the selected NaOH concentration is 0.5 mol•L. −1 .
[0021] Furthermore, the Pt loadings were 0.1%, 0.2%, and 0.5%.
[0022] This invention also discloses the application of the Pt / La2O2CO3 nanocatalyst prepared by the above method in the catalytic hydrogenation of CO2 to CO.
[0023] The beneficial effects of this invention are that both the Pt / La₂O₂CO₃-S catalyst and the Pt / La₂O₂CO₃-M catalyst prepared by this method exhibit good catalytic activity, selectivity, and stability, as well as good structural stability. The support for the Pt / La₂O₂CO₃-S catalyst is a single species of La₂O₂CO₃, while the support for the Pt / La₂O₂CO₃-M catalyst may be a mixture of multiple species of La₂O₂CO₃. This difference leads to different adsorption and activation capabilities of the catalysts for reactant molecules, resulting in the superior catalytic activity of the Pt / La₂O₂CO₃-S catalyst compared to the Pt / La₂O₂CO₃-M catalyst. Furthermore, the interaction between the Pt nanoparticles and the La₂O₂CO₃ support in both the Pt / La₂O₂CO₃-S and Pt / La₂O₂CO₃-M catalysts enhances their structural stability, thus contributing to their excellent catalytic stability.
[0024] The present invention has a simple preparation process and produces catalysts with high activity, selectivity and stability, effectively solving the problem of low activity and stability of Pt-based catalysts at high temperatures in the catalytic CO2 hydrogenation to CO reaction. Attached Figure Description
[0025] Figure 1 The CO2 conversion and CO selectivity of Pt / La2O2CO3-S and Pt / La2O2CO3-M catalysts with different Pt loadings in the embodiments of the present invention at 600 degrees Celsius.
[0026] Figure 2 The CO2 conversion and CO selectivity of Pt / La2O2CO3-S and Pt / La2O2CO3-M catalysts with a Pt loading of 0.2% at different temperatures are shown in the embodiments of the present invention.
[0027] Figure 3 The reaction rates of Pt / La2O2CO3-S and Pt / La2O2CO3-M catalysts with a Pt loading of 0.2% in the embodiments of the present invention at 600 degrees Celsius;
[0028] Figure 4 The recycling performance of Pt / La2O2CO3-S and Pt / La2O2CO3-M catalysts with a Pt loading of 0.2% in the embodiments of the present invention at 600 degrees Celsius;
[0029] Figure 5 The long-term stability of Pt / La2O2CO3-S and Pt / La2O2CO3-M catalysts with a Pt loading of 0.2% prepared in the embodiments of the present invention at 600 degrees Celsius;
[0030] Figure 6 These are TEM images of the catalysts prepared in embodiments of the present invention.
[0031] Figures (a) and (c) are TEM images of the Pt / La2O2CO3-S catalyst with a Pt loading of 0.2%, and Figures (b) and (d) are TEM images of the Pt / La2O2CO3-M catalyst with a Pt loading of 0.2%.
[0032] Figure 7 These are TEM images of the catalysts prepared in the embodiments of the present invention.
[0033] Among them, Figures (a) and (c) are TEM images of the Pt / La2O2CO3-S catalyst with a Pt loading of 0.2% after long-term stability testing, and Figures (b) and (d) are TEM images of the Pt / La2O2CO3-M catalyst with a Pt loading of 0.2% after long-term stability testing.
[0034] Figure 8 The images show the XRD patterns of Pt / La2O2CO3-S and Pt / La2O2CO3-M catalysts with a Pt loading of 0.2% prepared according to embodiments of the present invention after reaction.
[0035] Figure 9 The image shows the Raman spectroscopy results of Pt / La2O2CO3-S and Pt / La2O2CO3-M catalysts with a Pt loading of 0.2% prepared according to embodiments of the present invention after reaction.
[0036] Figure 10 H2-TPR diagrams of Pt / La2O2CO3-S and Pt / La2O2CO3-M catalysts with a Pt loading of 0.2% prepared in embodiments of the present invention;
[0037] Figure 11 The image shows the CO2-TPD of Pt / La2O2CO3-S and Pt / La2O2CO3-M catalysts with a Pt loading of 0.2% prepared according to embodiments of the present invention after the reaction. Detailed Implementation
[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0039] Example 1
[0040] A method for preparing Pt / La2O2CO3-S catalyst by supporting Pt nanoparticles with La2O2CO3 includes the following steps:
[0041] (1) Synthesis of La2O2CO3 single support La2O2CO3-S
[0042] 1 g of La(NO3)3•6H2O was added to 60 mL of deionized water, and the pH was adjusted to 12 with NaOH while stirring continuously. The stirring was continued for 1 h, and then the mixture was transferred to a 100 mL hydrothermal synthesis reactor and heated at 100 °C for 16 h. After cooling to room temperature, the mixture was filtered through a Buchner funnel to obtain a white precipitate, which was then washed with deionized water, dried at 80 °C for 10 h, and ground to obtain a white powder. Finally, the white powder was calcined in a muffle furnace at 500 °C for 4 h to obtain a single La2O2CO3 support, denoted as La2O2CO3-S.
[0043] (2) Preparation of Pt colloid
[0044] 0.07 g PtCl4, 0.09 g NaOH and 30 mL ethylene glycol were added sequentially to a 150 mL round-bottom flask and stirred at room temperature until they were mixed evenly. Then, while stirring, the mixture was refluxed in an oil bath at 180 °C for 4 h to obtain a black Pt colloid.
[0045] (3) A Pt / La2O2CO3-S catalyst with a Pt loading of 0.2% was prepared by colloidal deposition method.
[0046] 0.5 g of La2O2CO3-S was dispersed in 25 mL of deionized water and uniformly dispersed by stirring and sonication. Then, 0.67 mL of Pt colloid was added dropwise at room temperature and stirred continuously for 24 h. After centrifugation and washing with deionized water, the catalyst was dried at 80 °C for 10 h to obtain a Pt / La2O2CO3-S catalyst with a Pt loading of 0.2%.
[0047] Example 2
[0048] A method for preparing Pt / La2O2CO3-M catalyst by supporting Pt nanoparticles with La2O2CO3 includes the following steps:
[0049] (1) The process of synthesizing the mixed support La2O3 and La2O2CO3, La2O2CO3-M:
[0050] 1 g of La(NO3)3•6H2O was added to 60 mL of deionized water, and the pH was adjusted to 12 with NaOH while stirring continuously. The stirring was continued for 1 h, and then transferred to a 100 mL hydrothermal synthesis reactor. The mixture was heated at 100 °C for 8 h, cooled to room temperature, and filtered through a Buchner funnel to obtain a white precipitate. The precipitate was washed with deionized water, dried at 80 °C for 10 h, and ground to obtain a white powder. Finally, the white powder was calcined in a muffle furnace at 500 °C for 4 h to obtain a carrier of mixed La2O3 and La2O2CO3, denoted as La2O2CO3-M.
[0051] (2) Preparation of Pt colloid
[0052] 0.07 g PtCl4, 0.09 g NaOH and 30 mL ethylene glycol were added sequentially to a 150 mL round-bottom flask and stirred at room temperature until they were mixed evenly. Then, while stirring, the mixture was refluxed in an oil bath at 180 °C for 4 h to obtain a black Pt colloid.
[0053] (3) A Pt / La2O2CO3-M catalyst with a Pt loading of 0.2% was prepared by colloidal deposition method.
[0054] 0.5 g of La2O2CO3-M was dispersed in 25 mL of deionized water and uniformly dispersed by stirring and sonication. Then, 0.67 mL of Pt colloid was added dropwise at room temperature and stirred continuously for 24 h. After centrifugation and washing with deionized water, the catalyst was dried at 80 °C for 10 h to obtain a Pt / La2O2CO3-M catalyst with a Pt loading of 0.2%.
[0055] Example 3
[0056] The difference from the example is that the amount of Pt colloid added was 0.33 ml, resulting in a Pt / La2O2CO3-S catalyst with a Pt loading of 0.1%.
[0057] Example 4
[0058] The difference from the example is that the amount of Pt colloid added was 1.67 ml, resulting in a Pt / La2O2CO3-S catalyst with a Pt loading of 0.5%.
[0059] Example 5
[0060] The difference from the example is that the amount of Pt colloid added was 0.33 ml, resulting in a Pt / La2O2CO3-M catalyst with a Pt loading of 0.1%.
[0061] Example 6
[0062] The difference from the example is that the amount of Pt colloid added was 1.67 ml, resulting in a Pt / La2O2CO3-M catalyst with a Pt loading of 0.5%.
[0063] The Pt / La2O2CO3-S and Pt / La2O2CO3-M catalysts prepared in the above examples were applied to the catalytic hydrogenation of CO2 to CO reaction, and their performance was tested, specifically including:
[0064] (a) Reactivity test
[0065] In a fixed-bed reactor, 10 mg of 20-40 mesh catalyst was diluted with 500 mg of 20-40 mesh quartz sand. The mixture of quartz sand and catalyst was then loaded into a quartz reaction tube with an inner diameter of 8 mm. The quartz tube was then placed into the fixed-bed reactor, and a 5% H2 / N2 mixed gas was introduced at a flow rate of 60 mL / min. The reaction temperature was increased from room temperature to 600 °C at a rate of 10 °C / min, and the reduction treatment was carried out at this temperature for 1 h. Subsequently, the temperature was lowered to room temperature, and the flow rate was switched to a 20% CO2 / 60% H2 / 20% N2 mixed gas at a flow rate of 66.67 mL / min to evaluate the catalytic performance of CO2 hydrogenation to CO production. The reaction temperature was increased from room temperature to 400, 500, or 600 °C at a rate of 10 °C / min, and each reaction temperature was maintained for 1 h. Simultaneously, the outlet of the quartz reaction tube was connected to an online gas chromatograph, and the product content was analyzed using online gas chromatography. After the reaction is complete, wait for the reaction temperature to drop to room temperature, then shut off the corresponding gas flow, and then take out the catalyst after the reaction for corresponding catalyst structure characterization.
[0066] (ii) Cyclic performance test
[0067] Cyclic performance testing was also conducted in the same fixed-bed reactor. 10 mg of 20-40 mesh catalyst was diluted with 500 mg of 20-40 mesh quartz sand. The mixture of quartz sand and catalyst was then loaded into a quartz reaction tube with an inner diameter of 8 mm. The quartz tube was then placed into the fixed-bed reactor, and a 5% H2 / N2 mixed gas flow rate of 60 mL / min was introduced. The reaction temperature was increased from room temperature to 600 °C at a rate of 10 °C / min, and the reduction treatment was carried out at this temperature for 1 h. Subsequently, the temperature was lowered to room temperature, and the flow rate was switched to a 20% CO2 / 60% H2 / 20% N2 mixed gas flow rate of 66.67 mL / min for the catalytic hydrogenation of CO2 to CO reaction performance evaluation. The reaction temperature was increased from room temperature to 600 °C at a rate of 10 °C / min, and the reaction time was 1 h. Simultaneously, the outlet of the quartz reaction tube was connected to an online gas chromatograph, and the product content was analyzed using online gas chromatography. After the reaction was completed, the reaction temperature was allowed to decrease to room temperature. The reaction temperature was then raised from room temperature to 600°C at a rate of 10°C / min. This cycle was repeated three times to complete the cycle performance test.
[0068] (III) Long-term stability test
[0069] Long-term stability testing was also conducted in the same fixed-bed reactor. 10 mg of 20-40 mesh catalyst was diluted with 500 mg of 20-40 mesh quartz sand. The mixture of quartz sand and catalyst was then loaded into a quartz reaction tube with an inner diameter of 8 mm. The quartz tube was then placed into the fixed-bed reactor, and a 5% H2 / N2 mixed gas flow rate of 60 mL / min was introduced. The reaction temperature was increased from room temperature to 600 °C at a rate of 10 °C / min, and the reaction was subjected to reduction treatment at this temperature for 1 h. Subsequently, the temperature was lowered to room temperature, and the flow rate was switched to a 20% CO2 / 60% H2 / 20% N2 mixed gas flow rate of 66.67 mL / min for the catalytic hydrogenation of CO2 to CO reaction performance evaluation. The reaction temperature was increased from room temperature to 600 °C at a rate of 10 °C / min. Simultaneously, the outlet of the quartz reaction tube was connected to an online gas chromatograph, and the product content was analyzed using online gas chromatography. The reaction was carried out at 600℃ for 100 h. After the reaction was completed, the reaction temperature was lowered to room temperature, the corresponding gas flow was turned off, and then the catalyst after the reaction was taken out for corresponding catalyst structure characterization.
[0070] 1. Evaluation of catalytic activity
[0071] To determine the catalytic activity of Pt / La₂O₂CO₃-S and Pt / La₂O₂CO₃-M catalysts, the catalyst samples were evaluated under different Pt loadings and reaction temperatures. The results are as follows:
[0072] like Figure 1 As shown in (a), with the increase of Pt loading, the CO2 conversion rates of both Pt / La2O2CO3-S and Pt / La2O2CO3-M catalysts at 600°C increased, especially when the Pt loading increased from 0.1% to 0.2%, the increase in CO2 conversion rate of both Pt / La2O2CO3-S and Pt / La2O2CO3-M catalysts was the most significant. However, when the Pt loading was further increased to 0.5%, the increase in CO2 conversion rate of both Pt / La2O2CO3-S and Pt / La2O2CO3-M catalysts was smaller. Furthermore, as... Figure 1 As shown in (b), with increasing Pt loading, both the Pt / La2O2CO3-S and Pt / La2O2CO3-M catalysts maintained a CO selectivity of 99.9% at 600°C, indicating that Pt loading did not affect the CO selectivity of the catalysts. Therefore, the catalytic activity of the Pt / La2O2CO3-S and Pt / La2O2CO3-M catalysts was relatively better when the Pt loading was 0.2%. Furthermore, the CO2 conversion rate of the Pt / La2O2CO3-S catalyst with all prepared Pt loadings was higher than that of the Pt / La2O2CO3-M catalyst. For example, at 600°C, although all catalysts maintained a CO selectivity of 99.9%, the CO2 conversion rate of the Pt / La2O2CO3-S catalyst (38.16%) was approximately 9.73% higher than that of the Pt / La2O2CO3-M catalyst (28.43%).
[0073] like Figure 2 As shown in (a), at different reaction temperatures, the CO2 conversion rate of the Pt / La2O2CO3-S catalyst with a Pt loading of 0.2% is superior to that of the Pt / La2O2CO3-M catalyst, especially at 500°C and 600°C, where the CO2 conversion rate of the Pt / La2O2CO3-S catalyst with a Pt loading of 0.2% is more than 9% higher than that of the Pt / La2O2CO3-M catalyst. Similarly, at different reaction temperatures, such as Figure 2 As shown in (b), the CO selectivity of both Pt / La2O2CO3-S and Pt / La2O2CO3-M catalysts with a Pt loading of 0.2% is 99.9%, which indicates that the reaction temperature does not affect the CO selectivity of the catalyst.
[0074] like Figure 3 As shown, the Pt / La2O2CO3-S catalyst with a Pt loading of 0.2% (378.6 μmol / g) cat The reaction rate at 600°C was also higher than that of the Pt / La2O2CO3-M catalyst (282.1 μmol / g). cat The difference was approximately 96.5 umol / g (per s).cat / s.
[0075] The above results indicate that the prepared Pt / La2O2CO3-S catalyst has higher catalytic activity than the Pt / La2O2CO3-M catalyst.
[0076] 2. Evaluation of catalytic stability
[0077] To determine the catalytic stability of Pt / La₂O₂CO₃-S and Pt / La₂O₂CO₃-M catalysts, the catalyst samples were evaluated for their cycling performance and long-term stability. Test results:
[0078] like Figure 4 As shown, the CO2 conversion rates of Pt / La2O2CO3-S and Pt / La2O2CO3-M catalysts with a Pt loading of 0.2% after three cycles at 600°C are... Figure 4 (a) and CO selectivity Figure 4 (b) No significant decrease was observed, indicating that both Pt / La2O2CO3-S and Pt / La2O2CO3-M catalysts have good recyclability.
[0079] like Figure 5 As shown, the CO2 conversion rates of Pt / La2O2CO3-S and Pt / La2O2CO3-M catalysts with a Pt loading of 0.2% after continuous use at 600°C for 100 h are ( Figure 5 a) and CO selectivity ( Figure 5 b) No significant decrease was observed, indicating that both Pt / La2O2CO3-S and Pt / La2O2CO3-M catalysts have good long-term stability.
[0080] The above results indicate that both the Pt / La2O2CO3-S catalyst and the Pt / La2O2CO3-M catalyst exhibit good catalytic stability.
[0081] 3. Catalyst characterization
[0082] 3.1 Morphological Analysis
[0083] To understand the microstructure of Pt / La2O2CO3-S and Pt / La2O2CO3-M catalysts, the samples after reaction and after long-term stability evaluation were characterized by transmission electron microscopy (TEM).
[0084] like Figure 6 As shown in (a), the Pt / La2O2CO3-S catalyst with a Pt loading of 0.2% exhibits a nanoparticle structure with an overall diameter of approximately 50-100 nm. Furthermore, the catalyst surface is embedded with Pt particles smaller than 2 nm. Figure 6(c). In addition, such as Figure 6 As shown in (b), the Pt / La2O2CO3-M catalyst with a Pt loading of 0.2% also exhibits a nanoparticle structure, with an overall diameter of approximately 50-100 nm. Furthermore, the catalyst surface is also embedded with Pt particles smaller than 2 nm. Figure 6 (d). More noteworthy is the Pt / La2O2CO3-S catalyst with a Pt loading of 0.2% after undergoing a long-term stability test of 100 h. Figure 7 (a) and Pt / La2O2CO3-M catalyst Figure 7 (b) They all still exhibit a particle shape with a diameter of approximately 50-100 nm, and the Pt particles embedded on the surface of the catalyst are still approximately 2 nm in size, such as Figure 7 (c) and Figure 7 (d).
[0085] The above results indicate that the Pt / La2O2CO3-S and Pt / La2O2CO3-M catalysts have good structural stability, which may be an important reason for their excellent catalytic stability.
[0086] 3.2 Crystal structure analysis
[0087] To determine the crystal phase structure of Pt / La2O2CO3-S and Pt / La2O2CO3-M catalysts, the catalyst samples after the reaction were characterized by XRD and Raman spectroscopy.
[0088] like Figure 8 As shown, the XRD pattern of the Pt / La2O2CO3-S catalyst with a Pt loading of 0.2% exhibits obvious characteristic diffraction peaks of La2O2CO3. No other diffraction peaks were found, particularly those of Pt. This suggests that the support for the Pt / La2O2CO3-S catalyst may be a single species of La2O2CO3, and the Pt species may be well dispersed on the catalyst surface (or the low Pt loading may result in the absence of obvious characteristic diffraction peaks). Furthermore, the XRD pattern of the Pt / La2O2CO3-M catalyst with a Pt loading of 0.2% shows both relatively weak characteristic diffraction peaks of La2O2CO3 and obvious characteristic diffraction peaks of La2O3. Again, no characteristic diffraction peaks of Pt were found. This suggests that the support for the Pt / La2O2CO3-M catalyst may be a mixture of multiple species of La2O2CO3, and the Pt species may also be well dispersed on the catalyst surface (or the low Pt loading may result in the absence of obvious characteristic diffraction peaks).
[0089] In addition, such as Figure 9As shown, the Raman plot of the Pt / La2O2CO3-S catalyst with a Pt loading of 0.2% clearly shows the vibrational signals of the La2O2CO3 species (362 and 669 cm⁻¹). -1 Vibrational signals of the La2O2CO3 species in the Raman plot of the Pt / La2O2CO3-M catalyst with a Pt loading of 0.2% (362 and 669 cm⁻¹). -1 The concentration of La2O2CO3 is extremely weak. This further suggests that the support for the Pt / La2O2CO3-S catalyst may contain more La2O2CO3 species.
[0090] The above results indicate that the support for the Pt / La2O2CO3-S catalyst is a single species of La2O2CO3, while the support for the Pt / La2O2CO3-M catalyst may be a mixture of multiple species of La2O2CO3. This difference in support species may be an important reason for the difference in catalytic activity between the Pt / La2O2CO3-S and Pt / La2O2CO3-M catalysts.
[0091] 3.3 Structure-Property Relationship Analysis
[0092] To analyze the relationship between the structure and performance of Pt / La2O2CO3-S and Pt / La2O2CO3-M catalysts, the catalyst samples were characterized by H2-TPR and CO2-TPD.
[0093] like Figure 10 As shown, the H2-TPR spectra of Pt / La2O2CO3-S and Pt / La2O2CO3-M catalysts with a Pt loading of 0.2% show reduction peaks at 268 and 371 degrees, and the reduction peak of the Pt / La2O2CO3-S catalyst is more significant. This may be because the interaction between Pt species and La2O2CO3 is more moderate, making it easier to be reduced to metallic Pt species, which can more effectively activate H2 and thus promote the improvement of catalytic activity.
[0094] In addition, such as Figure 11 As shown, the CO2-TPD diagrams of the Pt / La2O2CO3-S and Pt / La2O2CO3-M catalysts with a Pt loading of 0.2% show obvious CO2 desorption signals starting at 496 and 445 degrees Celsius, respectively. Furthermore, the temperature at which the Pt / La2O2CO3-S catalyst begins to desorb CO2 is higher than that of the Pt / La2O2CO3-M catalyst, indicating that the Pt / La2O2CO3-S catalyst may have a stronger CO2 adsorption capacity than the Pt / La2O2CO3-M catalyst. Therefore, CO2 may be more easily activated on the Pt / La2O2CO3-S catalyst, thus improving catalytic activity.
[0095] The above results indicate that the Pt / La₂O₂CO₃-S catalyst may not only possess superior Pt species for H₂ activation, but also exhibit stronger CO₂ adsorption and activation capabilities. Therefore, the difference in support species between the Pt / La₂O₂CO₃-S and Pt / La₂O₂CO₃-M catalysts may lead to different adsorption and activation capabilities for reactant molecules, resulting in the superior catalytic activity of the Pt / La₂O₂CO₃-S catalyst compared to the Pt / La₂O₂CO₃-M catalyst.
[0096] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.
Claims
1. A method for preparing Pt / La2O2CO3 nanocatalysts by supporting Pt nanoparticles with La2O2CO3, characterized in that, The preparation of the Pt / La2O2CO3-S catalyst includes the following processes: a. Synthesis of La2O2CO3 single carrier La2O2CO3-S 1 g of La(NO3)3•6H2O was added to 60 mL of deionized water, and the pH was adjusted to 12 with NaOH while stirring continuously. The stirring was continued for 1 h, and then transferred to a 100 mL hydrothermal synthesis reactor. The mixture was heated at 100-120 °C for 16 h, cooled to room temperature, and filtered through a Buchner funnel to obtain a white precipitate. The precipitate was washed with deionized water, dried at 60-80 °C for 10 h, and ground to obtain a white powder. Finally, the white powder was calcined in a muffle furnace at 400-600 °C for 4 h to obtain a single La2O2CO3 support, denoted as La2O2CO3-S. b. Preparation of Pt colloids 0.05-0.10 g PtCl4, 0.08-0.12 g NaOH and 20-40 mL ethylene glycol were added sequentially to a 150 mL round-bottom flask. The mixture was stirred at room temperature until homogeneous. Then, while stirring, the mixture was refluxed in an oil bath at 180-200℃ for 2-4 hours to obtain a black Pt colloid. c. Preparation of Pt / La2O2CO3-S catalysts with different Pt loadings using colloidal deposition method 0.5 g of La2O2CO3-S was dispersed in 25 mL of deionized water and uniformly dispersed by stirring and sonication. Then, a certain amount of Pt colloid was added dropwise at room temperature and stirred continuously for 24 h. Subsequently, the Pt / La2O2CO3-S catalyst was obtained by centrifugation, washing with deionized water, and drying at 80 °C for 10 h.
2. The method for preparing Pt / La2O2CO3 nanocatalysts by supporting Pt nanoparticles with La2O2CO3 according to claim 1, characterized in that, It also includes the preparation of Pt / La2O2CO3-M catalyst, comprising the following processes: (1) The process of synthesizing the mixed support La2O3 and La2O2CO3, La2O2CO3-M: 1 g of La(NO3)3•6H2O was added to 60 mL of deionized water, and the pH was adjusted to 12 with NaOH while stirring continuously. The stirring was continued for 1 h, and then transferred to a 100 mL hydrothermal synthesis reactor. The mixture was heated at 100-120 °C for 8 h, and after cooling to room temperature, it was filtered through a Buchner funnel to obtain a white precipitate. The precipitate was washed with deionized water and dried at 60-80 °C for 10 h. After grinding, a white powder was obtained. Finally, the white powder was calcined in a muffle furnace at 400-600 °C for 4 h to obtain a carrier of mixed La2O3 and La2O2CO3, denoted as La2O2CO3-M. (2) Preparation of Pt colloid 0.05-0.10 g PtCl4, 0.08-0.12 g NaOH and 20-40 mL ethylene glycol were added sequentially to a 150 mL round-bottom flask. The mixture was stirred at room temperature until homogeneous. Then, while stirring, the mixture was refluxed in an oil bath at 180-200℃ for 2-4 hours to obtain a black Pt colloid. (3) Pt / La2O2CO3-M catalysts with different Pt loadings were prepared by colloidal deposition method. 0.5 g of La2O2CO3-M was dispersed in 25 mL of deionized water and uniformly dispersed by stirring and sonication. Then, a certain amount of Pt colloid was added dropwise at room temperature and stirred continuously for 24 h. Subsequently, the Pt / La2O2CO3-M catalyst was obtained by centrifugation, washing with deionized water, and drying at 80 °C for 10 h.
3. The method for preparing Pt / La2O2CO3 nanocatalysts by supporting Pt nanoparticles with La2O2CO3 according to claim 1 or 2, characterized in that, The selected NaOH concentration is 0.5 mol•L. −1 .
4. The method for preparing Pt / La2O2CO3 nanocatalysts by supporting Pt nanoparticles with La2O2CO3 according to claim 1 or 2, characterized in that, The Pt loadings are 0.1%, 0.2%, and 0.5%.
5. The application of the Pt / La2O2CO3 nanocatalyst prepared by the method according to claim 1 or 2 in the catalytic hydrogenation of CO2 to CO.