Preparation method and application of life-prolonging Pt-based nanofiber catalytic material
The preparation of porous SiZr-x aerogels and loaded with PtGa alloys was solved by air spray spinning, which solved the problems of scarce resources and reduced active sites of precious metal nanocatalysts, and achieved efficient and stable catalytic performance and long-life catalysts.
Patent Information
- Application Number
- CN202510085270.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-20
- Publication Date
- 2025-05-30
AI Technical Summary
In the catalytic reaction, precious metal nanocatalysts have problems such as scarcity of resources, high costs and reduced active sites, which affect the catalytic efficiency.
Porous SiZr-x aerogel was prepared by air spray spinning method, and PtGa alloy was loaded thereon, and the structure and electronic structure of the catalyst were regulated by doping ZrO2 to improve catalytic activity and stability.
The conversion rate and selectivity of Pt-based supported nanocatalysts in propane dehydrogenation reaction are significantly improved, the service life of the catalyst is extended, and the high temperature stability is improved.
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Abstract
Description
Technical Field
[0001] The present invention belongs to the preparation technology of supported nano-catalysts, and particularly relates to a life-extending Pt-based nanofiber catalytic material, its preparation method and application. Background Art
[0002] There are various types of nano-catalysts in the prior art, mainly including noble metal nano-catalysts, bimetallic nano-catalysts, and two-dimensional nano-catalysts and other major categories.
[0003] Noble metal nano-catalysts, such as gold (Au), platinum (Pt), and palladium (Pd), each exhibit unique catalytic properties. Gold (Au), with a half-filled outer d-orbital electron structure, is usually not easily chemically adsorbed to small molecules. However, by means of advanced technologies such as chemical plating, Au can be loaded on carbon nanotubes (CNTs) to prepare highly dispersed Au / CNTs nano-catalysts. Platinum (Pt), as an outstanding anode catalyst for methanol fuel cells, is easily affected by the strong adsorption of CO generated during the methanol oxidation process, resulting in blocked active sites. Palladium (Pd) performs well in catalyzing Sonogashira coupling reactions and other aspects. However, its utilization rate and dosage still need to be further optimized to achieve higher catalytic efficiency.
[0004] However, the application of noble metal nano-catalysts is severely restricted by limited resources. Noble metals have extremely low abundances in the earth's crust and scarce reserves, leading to high costs. In addition, the reduction of active sites is also a major challenge. For example, CO generated during the methanol oxidation process by Pt will firmly adsorb on the active sites, significantly reducing the effective number of active sites and thus affecting the catalytic efficiency.
[0005] Bimetallic nano-catalysts, such as Pt-Pd alloys, Pt-Ni alloys, and Pd-Co hollow nano-microspheres, exhibit more excellent catalytic properties through ingenious alloying designs. Pt-Pd alloys are outstanding in catalyzing methanol oxidation and have bifunctional active sites; Pt-Ni alloys can synthesize water-soluble octahedral structures through the synergistic effect of solvothermal action and crystal plane growth inhibitors; Pd-Co hollow nano-microspheres exhibit higher catalytic activity and stability when catalyzing Sonogashira coupling reactions.
[0006] Nevertheless, bimetallic nano-catalysts are not perfect either. The phenomenon of component segregation often occurs, that is, during the catalytic reaction process, the components of bimetallic nano-catalysts may segregate due to instability, thereby affecting the overall performance of the catalyst. In addition, high-boiling solvents and surfactants may coat the nano-particles during the preparation process, covering the active sites. Therefore, effective measures need to be taken to remove these surfactants to fully release the catalytic activity.
[0007] Two-dimensional nanocatalysts, such as graphene and graphitic carbon nitride (g-C 3 N 4 ), although often regarded as auxiliary catalysts or effective catalyst support materials, their unique two-dimensional structure also offers new possibilities for catalytic reactions. Graphene has attracted much attention due to its excellent physical and chemical properties; while g-C3N4 exhibits good chemical inertness in strong acid or strong base environments. However, problems such as its high charge carrier recombination rate, low specific surface area, and poor mass transfer severely limit the improvement of its catalytic efficiency.
[0008] In the exploration of enhancing the catalytic activity of nanocatalysts, researchers face many technical difficulties. The optimization of active sites is one of the keys. By reasonably adjusting the surface structure of the catalyst, such as introducing micro-nano structures like edge defects and pores, the density of active sites can be significantly increased. At the same time, by regulating the electronic structure of the catalyst through means such as element doping or heterojunction coupling, the reactivity of active sites can be further improved. In addition, the stability of the catalyst cannot be ignored. During the preparation and use process, effective measures need to be taken to prevent the agglomeration of nanocatalysts and maintain their high dispersion. Through methods such as surface modification or alloying, the corrosion resistance stability of the catalyst in harsh environments can be improved. The optimization of reaction conditions is also important, including precisely controlling the reaction temperature and pressure to improve the activity and selectivity of the catalyst; selecting a suitable reaction medium to improve the mass transfer efficiency of reactants.
[0009] It is worth mentioning that the nanofibers prepared by the gas jet spinning method, with their unique one-dimensional structure, high aspect ratio, high specific surface area, and porous structure, show great potential in the catalytic field. In particular, the hierarchical pore structure of these nanofibers can physically confine noble metals at high temperatures, effectively preventing their sintering and improving the high-temperature stability of the catalyst. However, the problem of metal migration and sintering inactivation caused by the weak interaction between the silica support and the metal remains a major bottleneck restricting its application scope. Therefore, creatively doping strong interaction oxides has become an effective strategy for anchoring active metal nanoparticles and improving the durability of supported nanocatalysts. This innovative idea provides a new direction for the design and preparation of nanocatalysts and is expected to push the development of catalytic science to a new level. Summary of the Invention
[0010] Technical problems to be solved: In view of the above existing technical problems, the present invention proposes a preparation method of a lifespan-extended Pt-based nanofiber catalytic material and its application in the catalytic field.
[0011] The present application provides a method for preparing a lifespan-extended Pt-based nanofiber catalytic material, and the preparation method includes the following steps:
[0012] S1. Preparation of precursor solution: Dissolve polyvinylpyrrolidone with a molecular weight of 50,000 - 1,300,000 in methanol and stir overnight to obtain a homogeneous and transparent polyvinylpyrrolidone methanol solution. Then, add silica, zirconia source materials, good solvents for the source materials, and additives to the polyvinylpyrrolidone methanol solution in sequence, and stir at room temperature until completely dissolved to obtain a homogeneous precursor solution;
[0013] S2. Preparation of composite SiZr - x aerogel: Use an air - jet spinning device to collect fibers with a clean non - woven gauze net as the receiver to prepare a composite SiZr - x aerogel;
[0014] S3. Preparation of porous composite SiZr - x aerogel: Place the composite SiZr - x aerogel obtained by air - jet spinning in step S2 in a muffle furnace for heat treatment to obtain a porous composite SiZr - x aerogel;
[0015] S4. Preparation of Pt - based supported nanocatalyst: Immerse 1 wt.% PtGa alloy salt solution onto the porous composite SiZr - x aerogel prepared in step S3, dry it, and then calcine it at 300 °C for 1 h with a heating rate of 5 °C / min to obtain a Pt - based supported nanocatalyst.
[0016] This application also provides a Pt - based supported nanocatalyst prepared according to the above - mentioned preparation method.
[0017] This application also provides the application of the above - mentioned lifespan - extended Pt - based nanofiber catalytic material in thermal catalytic reactions, specifically the application of the Pt - based supported nanocatalyst in the direct dehydrogenation reaction of propane.
[0018] Beneficial effects:
[0019] Compared with the prior art, the present invention shows the following remarkable advantages:
[0020] In this application, by finely regulating the key parameters in the air - jet spinning process, including flow rate, spraying distance, air pressure, environmental humidity, and spinning temperature, and combining with the precise proportion of the spinning solution components, nanofibers with a porous structure are successfully prepared. Further, by scientifically adjusting the proportion of the doping component ZrO 2 and loading PtGa alloy solution on the fibers respectively, Pt - based supported nanocatalysts with different catalytic activities for propane dehydrogenation reaction are obtained. The application of the air - jet spinning technology in this application not only realizes the rapid and uniform preparation of porous SiZr - x (x is a variable) aerogel, but also significantly improves the preparation efficiency and structural uniformity of the material. Particularly importantly, by cleverly doping an appropriate amount of ZrO 2, the conversion rate of the PtGa nanocatalyst prepared in this application for propane dehydrogenation reaction has been increased by about 2 times, and the selectivity has also been significantly increased by nearly 10%. In addition, in the continuous catalytic test for up to 100 hours, the deactivation constant of this catalyst is as low as 0.0045 h -1 , showing excellent catalytic stability and durability. In summary, through precise regulation of the gas jet spinning parameters and the doping component ratio, the present invention prepares an efficient and stable Pt-based supported nanocatalyst, providing a highly potential new catalytic material for catalytic reactions such as propane dehydrogenation.
[0021] The carefully prepared SiZr-x (x is a variable) nanofibers in this invention show a loose and porous and fine-structured characteristic after being calcined. This unique structural feature endows the material with a large specific surface area, thus providing abundant adsorption active sites. It is the existence of these active sites that enables the material to show excellent catalytic performance after loading the PtGa alloy. The best catalyst prepared in this application has a selectivity stably maintained at 98.8% during the catalytic reaction for up to 100 hours, an initial conversion rate as high as 43.2%, and a deactivation constant as low as 0.0045 h -1 , showing excellent catalytic performance and an extremely long service life.
[0022] In the precise field of catalyst design, the precise selection of the fiber pore size plays a decisive role in regulating the migration behavior of the noble metal platinum. Through in-depth research, we found that by reasonable pore size design, the movement range of platinum particles can be effectively restricted, thus significantly avoiding the unexpected aggregation phenomenon of platinum on the catalyst surface. In addition, through an innovative strategy, that is, doping zirconia (ZrO 2 ) with silica (SiO 2 ), the prepared composite support material shows a significant inhibitory effect on platinum sintering both physically and chemically. This doping strategy not only significantly improves the thermal stability of the carrier, but also greatly enhances its ability to anchor platinum particles, ensuring the integrity of the catalyst structure under high-temperature reaction conditions. It should be noted that the introduction of zirconia also promotes the effective transfer of electrons from the carrier material to platinum particles, and this process is crucial for maintaining the stability of platinum active substances. The stabilization of active substances has a direct and profound impact on the activity and selectivity of the catalyst. Therefore, the application of this composite support material is expected to play a key role in significantly improving the catalyst performance. In particular, the introduction of ZrO 2 effectively plays the role of anchoring the PtGa alloy, enabling this nanocatalyst to significantly restrict the migration of active metals in high-temperature catalytic reactions, thus greatly improving the durability of the noble metal-based nanocatalyst.
[0023] A Pt-based nanofiber catalytic material with the property of extended lifespan prepared in this application - the Pt-based supported nanocatalyst, is particularly suitable for use as a supported catalyst for propane dehydrogenation reaction. At a reaction temperature of 550 °C and a space velocity of 4.7 h -1 under the condition, when the feed gas composition is C 3 H 8 :H 2 :Ar = 1:1:8, within the first 10 hours of the reaction, the conversion rate of this catalyst is stably maintained above 40%, and this performance is nearly twice that of the PtGa / SiO 2 nanocatalyst without doping design. Meanwhile, its selectivity is as high as 98.8%, which is nearly 10% higher than that of the PtGa / SiO 2 nanocatalyst without doping design. Thus, it can be seen that the Pt-based supported nanocatalyst with the property of extended lifespan prepared in this application exhibits excellent performance in both catalytic activity and selectivity. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 It is a schematic diagram of the synthesis of the gas jet spinning device in an embodiment of this application.
[0025] Figure 2 It is a physical picture of the SiZr-x aerogel in an embodiment of this application.
[0026] Figure 3 It is a TEM image of the nanocatalyst prepared in Comparative Example 1 of this application.
[0027] Figure 4 It is a TEM image of the nanocatalyst prepared in Comparative Example 2 of this application.
[0028] Figure 5 It is a TEM image of the nanocatalyst prepared in Example 1 of this application.
[0029] Figure 6 It is a TEM image of the nanocatalyst prepared in Example 2 of this application.
[0030] Figure 7 It is a TEM image of the nanocatalyst prepared in Example 3 of this application
[0031] Figure 8 It is a TEM image of the nanocatalyst prepared in Example 4 of this application.
[0032] Figure 9 It is a TEM image of the nanocatalyst prepared in Example 5 of this application.
[0033] Figure 10 The 10h catalytic activity diagram of the nanocatalyst prepared in Comparative Example 1 of this application
[0034] Figure 11 10h catalytic activity diagram of the nano-catalyst prepared in Comparative Example 2 of this application
[0035] Figure 12 10h catalytic activity diagram of the nano-catalyst prepared in Example 1 of this application
[0036] Figure 13 100h catalytic activity diagram of the nano-catalyst prepared in Example 1 of this application
[0037] Figure 14 10h catalytic activity diagram of the nano-catalyst prepared in Example 2 of this application
[0038] Figure 15 10h catalytic activity diagram of the nano-catalyst prepared in Example 3 of this application
[0039] Figure 16 10h catalytic activity diagram of the nano-catalyst prepared in Example 4 of this application
[0040] Figure 17 10h catalytic activity diagram of the nano-catalyst prepared in Example 5 of this application Detailed implementation manners
[0041] The preferred embodiments of the present invention will be described in detail below in conjunction with the embodiments. It should be understood that the following embodiments are given only for the purpose of illustration and are not used to limit the scope of the present invention. Those skilled in the art can make various modifications and substitutions to the present invention without departing from the purpose and spirit of the present invention.
[0042] The experimental methods used in the following examples are all conventional methods unless otherwise specified.
[0043] The materials, reagents, etc. used in the following examples can be obtained from commercial channels unless otherwise specified.
[0044] An embodiment of this application provides a preparation method of an anti-aging Pt-based nanofiber catalytic material. For the preparation schematic diagram, see Figure 1 , and the preparation method includes the following steps:
[0045] S1, preparing a precursor solution: Dissolve polyvinylpyrrolidone with a molecular weight of 50,000 - 1,300,000 in methanol, stir overnight to obtain a uniform and transparent polyvinylpyrrolidone methanol solution, and sequentially add silicon oxide, zirconium oxide material sources, good solvents and auxiliaries of the material sources to the polyvinylpyrrolidone methanol solution, and stir at room temperature until it is completely dissolved to obtain a uniform precursor solution;
[0046] S2. Preparation of composite SiZr-x aerogel: Using an air-jet spinning device, a clean non-woven gauze net is used as a receiver to collect fibers, and the composite SiZr-x aerogel is prepared;
[0047] S3. Preparation of porous composite SiZr-x aerogel: The composite SiZr-x aerogel obtained by air-jet spinning in step S2 is placed in a muffle furnace for heating treatment to obtain a porous composite SiZr-x aerogel;
[0048] S4. Preparation of Pt-based supported nano-catalyst. Immerse 1 wt.% PtGa alloy salt solution onto the porous composite SiZr-x aerogel prepared in step S3. After drying, calcine at 300 °C for 1 h with a heating rate of 5 °C / min to obtain the Pt-based supported nano-catalyst. For the physical product obtained, see Figure 2 .
[0049] In one embodiment, the Pt-based supported nano-catalyst is a PtGa / SiZr-x catalyst, where the value range of x is from 0 to 100, and it is the mass percentage of ZrO 2 in the total mass of SiZr-x
[0050] In one embodiment, the mass fraction of the polyvinylpyrrolidone methanol solution in step S1 is 20 wt.% - 30 wt.%.
[0051] In one embodiment, the mass fraction of the polyvinylpyrrolidone methanol solution in step S1 is preferably 24 wt.%.
[0052] In one embodiment, the silica material source is 3-aminopropyltriethoxysilane, the zirconia material source is zirconium acetylacetonate, and the good solvent for the silica and zirconia material sources is methanol.
[0053] In one embodiment, the auxiliary agent is cetyltrimethylammonium bromide or poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer.
[0054] In one embodiment, the parameters of the air-jet spinning device in S2 are as follows: the set air pressure is 0.3 mbar, the distance between the metal needle and the wire collector is 25 cm, the flow rate is 10 mL / h, where the spinning environment temperature is 25 °C and the humidity is 40%.
[0055] In one embodiment, in S3, the heating treatment is as follows: first heat up to 200 °C at a rate of 2 °C / min, then heat up to 500 °C at a rate of 1 °C / min, and finally heat up to 800 °C at a rate of 3 °C / min for calcination for 120 min.
[0056] In one embodiment, the pore size of the non-woven gauze net is 2 mm or 1 mm.
[0057] An embodiment of the present application provides an anti-aging Pt-based nanofiber catalytic material prepared according to the preparation method.
[0058] An embodiment of the present application provides the application of the anti-aging Pt-based nanofiber catalytic material in a thermal catalytic reaction, specifically the application of the Pt-based supported nanocatalyst in the direct dehydrogenation reaction of propane.
[0059] Comparative Example 1:
[0060] a. Preparation of SiO 2 aerogel material:
[0061] First, prepare the electrospinning precursor solution. Mix 1.9 g of PVP powder, 0.1 g of CTAB, 0.1 g of P123 with 20 mL of methanol, and add 5.64 mL of KH550 to the above solution, and stir overnight to obtain a uniform and transparent precursor solution.
[0062] Second, under the conditions of a gas pressure of 0.3 mbar, a distance of 25 cm between the metal needle and the metal mesh, and a flow rate of 10 mL / h, use a non-woven fabric with a pore diameter of 1 mm and a thickness of 0.5 mm as the receiver to collect fibers, and require the spinning environment temperature to be 25 °C and the humidity to be 40%.
[0063] The as-spun PVP / KH550 is first heated to 200 °C at a rate of 2 °C / min in a muffle furnace, then heated to 500 °C at a rate of 1 °C / min, and finally heated to 800 °C at a rate of 3 °C / min and calcined for 120 min to obtain porous SiO 2 aerogel. Grind it into powder with a mortar and set aside.
[0064] b. Propane dehydrogenation performance test:
[0065] Impregnate the Pt Ga salt solution with the SiO 2 aerogel powder, spin-dry it, and then heat it to 300 °C at a heating rate of 5 °C / min and calcine for 1 h. After taking it out, weigh 100 mg of the catalyst and 1200 mg of quartz sand (50-80 mesh) and mix them evenly in a quartz tube with an inner diameter of 9 mm. Perform propane dehydrogenation test in a vertical fixed bed, reaction conditions: 0.1 g of catalyst, 823 K, 10% C 3 H 8 / 10% H 2 / 80% Ar feed gas, total flow rate of 40 mL / min at atmospheric pressure, and space velocity of propane of 4 h -1 .
[0066] The experimental results show that the porous SiO 2As an innovative carrier material, aerogel has been successfully applied to the Pt-based catalyst system. For the characterization results of transmission electron microscopy (TEM), please refer to the appendix Figure 3 , which clearly reveals the microstructure characteristics of the porous SiO 2 aerogel carrier. The abundant pore structure inside provides an ideal platform for the uniform dispersion of Pt nanoparticles.
[0067] When further evaluating the catalytic performance of this catalyst, referring to Figure 10 the data comparison chart, it can be intuitively seen that when pure SiO 2 is used as the carrier, although it shows certain catalytic activity, the conversion rate only reaches 41%, and the selectivity is maintained at the level of 90%. This result indicates that although pure SiO 2 as the carrier has certain application potential, its catalytic performance still needs to be improved, which also provides research motivation and direction for subsequent exploration of more efficient carrier materials, such as porous SiO 2 aerogel.
[0068] Comparative Example 2:
[0069] a. Preparation of ZrO 2 aerogel material by air jet spinning method:
[0070] First, prepare the air jet spinning precursor solution. Mix 1.9 g of PVP powder, 0.1 g of CTAB, 0.1 g of P123 with 20 mL of methanol, and add 4.5 g of Zr(ac ac) 4 to the above solution, and stir overnight to obtain a pale yellow uniform and transparent precursor solution.
[0071] Second, under the conditions of a gas pressure of 0.3 mbar, a distance of 25 cm between the metal needle and the metal mesh, and a flow rate of 10 mL / h, use a non-woven fabric with a pore diameter of 1 mm and a thickness of 0.5 mm as the receiver to collect fibers, and require the spinning environment temperature to be 25°C and the humidity to be 40%.
[0072] The as-spun PVP / Zr(ac ac) 4 is first heated to 200°C at a rate of 2°C / min in a muffle furnace, then heated to 500°C at a rate of 1°C / min, and finally heated to 800°C at a rate of 3°C / min and calcined for 120 min to obtain porous ZrO 2 aerogel. Grind it into powder with a mortar and set aside.
[0073] b. Propane dehydrogenation performance test:
[0074] Mix the Pt Ga salt solution with ZrO 2The aerogel powder was co-impregnated, and after rotary evaporation and drying, it was heated to 300 °C at a heating rate of 5 °C / min and calcined for 1 h. After taking it out, 100 mg of the catalyst and 1200 mg of quartz sand (50-80 mesh) were weighed and mixed evenly in a quartz tube with an inner diameter of 9 mm. The propane dehydrogenation test was carried out in a vertical fixed-bed. The reaction conditions were: 0.1 g of catalyst, 823 K, 10% C 3 H 8 / 10% H 2 / 80% Ar feed gas, and the total flow rate was 40 mL / min under atmospheric pressure. The space velocity of propane was 4.7 h -1 .
[0075] The experimental results show that the porous ZrO 2 aerogel, as a potential carrier material, was applied to the Pt-based catalyst system. It was characterized by transmission electron microscopy (TEM). The specific results are shown in Figure 4 , and this figure shows the fine microstructure of the porous ZrO 2 aerogel carrier. Its highly porous internal characteristics provide a good environment for the loading and dispersion of Pt nanoparticles.
[0076] When evaluating the catalytic activity of this catalyst, referring to the Figure 11 data comparison chart, it can be observed that when pure ZrO 2 was used as the carrier, its catalytic activity was poor, the conversion rate was only 32%, and at the same time the selectivity was relatively low, being 88.8%. This result reminds us that although pure ZrO 2 has a certain application basis as a carrier material, its catalytic performance still needs to be improved, which also provides a research direction and motivation for the subsequent exploration of more efficient catalyst carrier materials.
[0077] Example 1:
[0078] a. Prepare the SiZr-5 (ZrO 2 / SiO 2 = 5 wt.%) aerogel material by the gas spraying spinning method:
[0079] First, prepare the gas spraying spinning precursor solution. 1.9 g of PVP (polyvinylpyrrolidone) powder, 0.1 g of CTAB (cetyltrimethylammonium bromide), 0.1 g of P123 (polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer) were mixed with 20 mL of ethanol and methanol. 4.5 mL of KH550 (γ-aminopropyltriethoxysilane) and 0.242 g of Zr(ac ac)4 (zirconium acetylacetonate) were added to the above solution, and stirred overnight to obtain a pale yellow uniform and transparent precursor solution.
[0080] Secondly, under the conditions of a pressure of 0.3 mbar, a distance of 25 cm between the metal needle and the metal mesh, and a flow rate of 10 mL / h, a non-woven fabric with a pore size of 1 mm and a thickness of 0.5 mm was used as the receiver to collect fibers. The spinning environment was required to have a temperature of 25 °C and a humidity of 40%.
[0081] The PVP / KH550 / Zr(ac ac) obtained by electrospinning 4 was first heated in a muffle furnace to 200 °C at a rate of 2 °C / min, then to 500 °C at a rate of 1 °C / min, and finally to 800 °C at a rate of 3 °C / min and calcined for 120 min to obtain porous SiZr-5 aerogel. It was ground into powder with a mortar for standby.
[0082] b. Propane dehydrogenation performance test:
[0083] The prepared Pt Ga salt solution was co-impregnated with the SiZr-5 aerogel powder. After rotary evaporation and drying, it was heated to 300 °C at a heating rate of 5 °C / min and calcined for 1 h. After taking it out, 100 mg of the catalyst and 1200 mg of quartz sand (50-80 mesh) were weighed and mixed evenly in a quartz tube with an inner diameter of 9 mm. Propane dehydrogenation test was carried out in a vertical fixed bed. The reaction conditions were: 0.1 g of catalyst, 823 K, 10% C 3 H 8 / 10% H 2 / 80% Ar feed gas, the total flow rate was 40 mL / min under atmospheric pressure, and the space velocity of propane was 4 h -1 .
[0084] The experimental results show that the porous SiZr-5 aerogel, as the support of the Pt-based catalyst, exhibits unique advantages when carrying the Pt-based catalyst. The characterization results of its microstructure by transmission electron microscopy (TEM) are specifically shown in the appendix Figure 5 . It clearly reveals its highly porous and uniform structure, which provides rich active sites and good mass transfer paths for the catalyst. Further, its activity test results, such as Figure 12 shown, intuitively present the performance of this catalyst system under different reaction conditions. It is particularly worth mentioning that the activity performance of this catalyst in the continuous operation test for up to 100 hours is detailed as Figure 13 shown. It not only maintains a high degree of stability but also shows significant superiority in catalytic efficiency. Specifically, its conversion rate reaches 43%, which is much higher than the average level of similar catalysts; at the same time, the selectivity is as high as 98.8%, almost achieving complete selective conversion of the target product, reflecting extremely high catalytic precision. Particularly crucial is that its deactivation constant is as low as 0.0045 h -1, this extremely low value indicates that the catalyst has excellent anti-deactivation ability and can maintain high catalytic activity during long-term operation, providing a solid experimental basis for industrial applications.
[0085] Example 2:
[0086] a. Prepare SiZr-10 (ZrO 2 / SiO 2 = 10 wt.%) aerogel material:
[0087] First, prepare the electrospinning precursor solution. Mix 1.9 g of PVP (polyvinylpyrrolidone) powder, 0.1 g of CTAB (cetyltrimethylammonium bromide), 0.1 g of P123 (polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer) with 20 mL of methanol. Add 4.5 mL of KH550 (γ-aminopropyltriethoxysilane) and 0.52 g of Zr(ac ac) 4 (zirconium acetylacetonate) into the above solution and stir overnight to obtain a pale yellow, uniform and transparent precursor solution.
[0088] Secondly, under the conditions of a pressure of 0.3 mbar, a distance of 25 cm between the metal needle and the metal mesh, and a flow rate of 10 mL / h, use a non-woven fabric with a pore size of 1 mm and a thickness of 0.5 mm as the receiver to collect fibers. The electrospinning environment temperature is required to be 25 °C and the humidity is 40%.
[0089] The electrospun PVP / KH550 / Zr(ac ac) 4 is first heated to 200 °C at a rate of 2 °C / min in a muffle furnace, then heated to 500 °C at a rate of 1 °C / min, and finally heated to 800 °C at a rate of 3 °C / min and calcined for 120 min to obtain porous SiZr-10 aerogel. Grind it into powder with a mortar and set aside.
[0090] b. Propane dehydrogenation performance test:
[0091] Co-impregnate the prepared Pt Ga salt solution with the SiZr-10 aerogel powder. After rotary evaporation and drying, heat it to 300 °C at a heating rate of 5 °C / min and calcine for 1 h. After taking it out, weigh 100 mg of the catalyst and 1200 mg of quartz sand (50 - 80 mesh) and mix them evenly in a quartz tube with an inner diameter of 9 mm. Conduct propane dehydrogenation test in a vertical fixed bed. Reaction conditions: 0.1 g of catalyst, 823 K, 10% C 3 H 8 / 10% H 2 / 80% Ar feed gas, total flow rate of 40 mL / min at atmospheric pressure, and propane space velocity of 4 h -1 .
[0092] The experimental results show that the porous SiZr-10 aerogel, as the support of the Pt-based catalyst, the results of its active electron micrographs are referred to Figure 6 The test results are shown in Figure 14 As shown, the experimental results clearly show that in this study, the porous SiZr-10 aerogel exhibits excellent performance as the support of the Pt-based catalyst. This aerogel is a material with a special microstructure and excellent physical and chemical properties. Its porous structure provides an ideal loading environment for the Pt-based catalyst, thus playing a crucial role in promoting the catalytic reaction. Through a series of rigorous experimental tests and data analysis, we obtained detailed performance data on this catalyst system.
[0093] When conducting the activity test on this catalyst system, advanced electron microscopy techniques were used for observation and analysis. The results of its active electron micrographs are referred to Figure 6 The test methods and related information shown, the final results of the active electron micrographs are as follows, and the detailed situation can be seen in Figure 14 As shown. It can be seen from these experimental results that during the reaction process, this catalyst system shows excellent performance. Specifically, its conversion rate reaches an impressive 43%, which means that in this catalytic reaction, a considerable proportion of the reactants are successfully converted into products, reflecting the high efficiency of this catalyst system in converting reactants.
[0094] At the same time, the selectivity of this catalyst system is as high as 90.8%. This is a very important indicator, indicating that during the reaction process, this catalyst is more inclined to produce the target product rather than a large number of by-products, further highlighting the advantage of this catalyst in terms of selectivity. Considering the two key indicators of conversion rate and selectivity, this Pt-based catalyst based on porous SiZr-10 aerogel as the support shows excellent catalytic performance. This excellent catalytic performance not only provides strong data support for our current research, but also lays a solid foundation for its practical application in related fields. For example, in the fields of chemical engineering, energy, environment, etc., this catalyst is expected to show broad application prospects and bring new ideas and methods for solving the catalytic problems in related reaction processes.
[0095] Example 3:
[0096] a. Prepare the SiZr-15 (ZrO 2 / SiO 2 = 15 wt.%) aerogel material by the gas spraying spinning method:
[0097] First, prepare the gas spraying spinning precursor solution. Mix 1.9 g of PVP powder, 0.1 g of CTAB, 0.1 g of P123 with 20 mL of methanol. Mix 4.5 mL of KH550 and 0.81 g of Zr(ac ac)4 Add it to the above solution and stir overnight to obtain a pale yellow, homogeneous and transparent precursor solution.
[0098] Secondly, under the conditions of a pressure of 0.3 mbar, a distance of 25 cm between the metal needle and the metal mesh, and a flow rate of 10 mL / h, use a non-woven fabric with a pore diameter of 1 mm and a thickness of 0.5 mm as the receiver to collect fibers. The spinning environment temperature is required to be 25 °C and the humidity is 40%.
[0099] The PVP / KH550 / Zr(ac ac) obtained by electrospinning 4 In a muffle furnace, first heat it to 200 °C at a rate of 2 °C / min, then heat it to 500 °C at a rate of 1 °C / min, and finally heat it to 800 °C at a rate of 3 °C / min and calcine for 120 min to obtain porous SiZr-15 aerogel. Grind it into powder with a mortar for standby.
[0100] b. Propane dehydrogenation performance test:
[0101] Co-impregnate the prepared Pt Ga salt solution with the SiZr-15 aerogel powder. After rotary evaporation and drying, heat it to 300 °C at a heating rate of 5 °C / min and calcine for 1 h. After taking it out, weigh 100 mg of the catalyst and 1200 mg of quartz sand (50-80 mesh) and mix them evenly in a quartz tube with an inner diameter of 9 mm. Carry out propane dehydrogenation test in a vertical fixed bed. Reaction conditions: 0.1 g of catalyst, 823 K, 10% C 3 H 8 / 10% H 2 / 80% Ar feed gas, total flow rate of 40 mL / min under atmospheric pressure, and space velocity of propane of 4 h -1 .
[0102] The experimental results show that the porous SiZr-15 aerogel, as an innovative carrier material, exhibits good application potential in the Pt-based catalyst system. It is characterized by transmission electron microscopy (TEM). For specific results, see Figure 7 , which clearly reveals the fine microstructure of the porous SiZr-15 aerogel carrier. The uniformly distributed porous structure inside provides an ideal platform for the effective loading and highly dispersing of Pt nanoparticles.
[0103] When testing its catalytic activity, the results are as shown in the following figure Figure 15 shown. The experimental data show that the conversion rate of this catalyst is close to 40%, the selectivity is stable at 90%, and it shows good stability during the long-term reaction process. This result not only verifies the effectiveness of the porous SiZr-15 aerogel as a Pt-based catalyst carrier, but also provides strong support for its application in actual catalytic reactions.
[0104] Example 4:
[0105] a. Prepare SiZr-20 (ZrO 2 / SiO 2 = 20 wt.%) aerogel material:
[0106] First, prepare the electrospinning precursor solution. Mix 1.9 g of PVP powder, 0.1 g of CTAB, 0.1 g of P123 with 20 mL of methanol. Add 4.5 mL of KH550 and 1.15 g of Zr(ac ac) 4 to the above solution and stir overnight to obtain a light yellow, homogeneous and transparent precursor solution.
[0107] Secondly, under the conditions of a pressure of 0.3 mbar, a distance of 25 cm between the metal needle and the metal mesh, and a flow rate of 10 mL / h, use a non-woven fabric with a pore diameter of 1 mm and a thickness of 0.5 mm as the receiver to collect fibers. The spinning environment temperature is required to be 25 °C and the humidity is 40%.
[0108] The electrospun PVP / KH550 / Zr(ac ac) 4 is first heated to 200 °C at a rate of 2 °C / min in a muffle furnace, then heated to 500 °C at a rate of 1 °C / min, and finally heated to 800 °C at a rate of 3 °C / min and calcined for 120 min to obtain porous SiZr-20 aerogel. Grind it into powder with a mortar and set aside.
[0109] b. Propane dehydrogenation performance test:
[0110] Co-impregnate the prepared Pt Ga salt solution with the SiZr-20 aerogel powder. After rotary evaporation and drying, heat it to 300 °C at a heating rate of 5 °C / min and calcine for 1 h. Take out and weigh 100 mg of the catalyst and 1200 mg of quartz sand (50 - 80 mesh) and mix them evenly in a quartz tube with an inner diameter of 9 mm. Perform propane dehydrogenation test in a vertical fixed bed. Reaction conditions: 0.1 g of catalyst, 823 K, 10% C 3 H 8 / 10% H 2 / 80% Ar feed gas, total flow rate of 40 mL / min under atmospheric pressure, and space velocity of propane of 4 h -1 .
[0111] The experimental results show that the porous SiZr-20 aerogel, as an excellent carrier material, plays a key role in the Pt-based catalyst system. The detailed transmission electron microscopy (TEM) image results are referred to Figure 8, This figure intuitively shows the unique microstructural characteristics of the porous SiZr-20 aerogel support, further confirming its highly interconnected porous network inside, which provides an ideal microenvironment for the uniform distribution and efficient catalysis of Pt nanoparticles.
[0112] The results of the activity test are shown in the following figure Figure 16 as shown. The data shows that the conversion rate of this catalyst is 45%, and the selectivity is as high as 90.3%. Compared with other support materials, its conversion rate performance is particularly excellent. This result not only highlights the excellent performance of the porous SiZr-20 aerogel as a Pt-based catalyst support, but also lays a solid foundation for its wide application in the catalytic field.
[0113] Example 5:
[0114] a. Prepare a SiZr-30 (ZrO 2 / SiO 2 = 30 wt.%) aerogel material by the gas electrospinning method:
[0115] First, prepare the gas electrospinning precursor solution. Mix 1.9 g of PVP powder, 0.1 g of CTAB, 0.1 g of P123 with 20 mL of methanol, and add 4.5 mL of KH550 and 1.97 g of Zr(ac ac) 4 to the above solution, and stir overnight to obtain a light yellow homogeneous and transparent precursor solution.
[0116] Secondly, under the conditions of a pressure of 0.3 mbar, a distance of 25 cm between the metal needle and the metal mesh, and a flow rate of 10 mL / h, use a non-woven fabric with a pore diameter of 1 mm and a thickness of 0.5 mm as the receiver to collect the fibers. The spinning environment temperature is required to be 25 °C and the humidity is 40%.
[0117] The as-spun PVP / KH550 / Zr(ac ac) 4 is first heated to 200 °C at a rate of 2 °C / min in a muffle furnace, then heated to 500 °C at a rate of 1 °C / min, and finally heated to 800 °C at a rate of 3 °C / min and calcined for 120 min to obtain a porous SiZr-30 aerogel. Grind it into powder with a mortar and set aside.
[0118] b. Propane dehydrogenation performance test:
[0119] Co-impregnate the prepared Pt Ga salt solution with the SiZr-30 aerogel powder, spin-evaporate and dry it, then heat it to 300 °C at a heating rate of 5 °C / min and calcine for 1 h. After taking it out, weigh 100 mg of the catalyst and 1200 mg of quartz sand (50-80 mesh) and mix them evenly in a quartz tube with an inner diameter of 9 mm. Carry out propane dehydrogenation test in a vertical fixed bed. Reaction conditions: 0.1 g of catalyst, 823 K, 10% C3 H 8 / 10% H 2 / 80% Ar feed gas, total flow rate of 40 mL / min at atmospheric pressure, and propane space velocity of 4 h -1 .
[0120] The experimental results show that the porous SiZr-30 aerogel, as a support material for Pt-based catalysts, exhibits excellent catalytic performance. The characterization results of its transmission electron microscope (TEM) can be specifically seen in Figure 9 , which clearly shows the highly ordered and interconnected porous structure inside the porous SiZr-30 aerogel support, providing an ideal microenvironment for the uniform loading and efficient catalysis of Pt nanoparticles.
[0121] Further testing its activity, the results are shown in the following figure Figure 17 As shown, the conversion rate of this catalyst is 40.3%, and the selectivity is as high as 90.6%, with particularly superior conversion performance. This result not only verifies the effectiveness of the porous SiZr-30 aerogel as a support for Pt-based catalysts, but also provides strong support for its wide application in catalytic reactions..
[0122] In summary, after loading noble metals, the Pt Ga / Si Zr-x nanocatalyst prepared in this invention is applied to the propane dehydrogenation to propylene reaction, and its performance is excellent. Especially, the Pt Ga / SiZr-5 nanocatalyst at 550 °C and 4.7 h -1 space velocity, with the feed gas being C 3 H 8 :H 2 :Ar = 1:1:8, within 10 h of the reaction, its conversion rate remains at 43.1%, and the selectivity is 98.8%. Its activity is much higher than that of Pt Ga / SiO 2 . This is mainly attributed to the high surface area of SiZr-5, which is 385.858 m 2 / g, making it easier to disperse noble metals and playing a role in physically confining and anti-sintering. On the other hand, the surface hydroxyl content of the SiZr-5 aerogel is also greater than that of SiO 2 , so this material has superior catalytic performance.
[0123] The above is only the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.
Claims
1. A method for preparing a life-extending Pt-based nanofiber catalytic material, characterized in that: The preparation method comprises the following steps: S1, preparing a precursor solution: dissolving polyvinyl pyrrolidone with a molecular weight of 50,000-1,300,000 in methanol, stirring overnight to obtain a uniform and transparent polyvinyl pyrrolidone methanol solution, sequentially adding silicon oxide and zirconium oxide material sources and a good solvent and an auxiliary agent of the material sources to the polyvinyl pyrrolidone methanol solution, stirring at room temperature to completely dissolve them, and obtaining a uniform precursor solution; S2, preparing composite SiZr-x aerogel: using an air-jet spinning device, using a clean non-woven gauze mesh as a receiver to collect fibers, and preparing a composite Si Zr-x aerogel; S3, preparing a porous composite SiZr-x aerogel: placing the composite SiZr-x aerogel obtained by air-jet spinning in step S2 in a muffle furnace for heating treatment to obtain a porous composite SiZr-x aerogel; S4, preparing a Pt-based supported nanocatalyst, impregnating a 1wt.% Pt Ga alloy salt solution into the porous composite SiZr-x aerogel obtained in step S3, drying, calcining at 300°C for 1h with a heating rate of 5°C / min to obtain a Pt-based supported nanocatalyst.
2. The method for preparing a life-extending Pt-based nanofiber catalytic material according to claim 1, characterized in that: The Pt-based supported nanocatalyst is a Pt Ga / Si Zr-x catalyst, wherein x ranges from 0 to 100 and is the mass percentage of ZrO2 in the total mass of SiZr-x.
3. The method for preparing a life-extending Pt-based nanofiber catalytic material according to claim 1, characterized in that: The mass fraction of the polyvinyl pyrrolidone methanol solution in step S1 is 20wt.%-30wt.%.
4. The method for preparing a life-extending Pt-based nanofiber catalytic material according to claim 1, characterized in that: The silicon oxide material source is 3-aminopropyltriethoxysilane, the zirconium oxide material source is zirconium acetylacetonate, and the good solvent of the silicon oxide and zirconium oxide material sources is methanol.
5. The method for preparing the life-extending Pt-based nanofiber catalytic material according to claim 1, characterized in that The auxiliary agent is hexadecyltrimethylammonium bromide or polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer.
6. The method for preparing a life-extending Pt-based nanofiber catalytic material according to claim 1, characterized in that: The parameters of the air-jet spinning device in S2 are: the set air pressure is 0.3 mbar, the distance between the metal needle and the collector is 25 cm, the flow rate is 10 mL / h, and the spinning environment temperature is 25° C. and the humidity is 40%.
7. The method for preparing a life-extending Pt-based nanofiber catalytic material according to claim 1, characterized in that: In S3, the temperature raising treatment is to first raise the temperature to 200°C at 2°C / min, then raise the temperature to 500°C at 1°C / min, and finally raise the temperature to 800°C at 3°C / min and calcine for 120 minutes.
8. The method for preparing a life-extending Pt-based nanofiber catalytic material according to claim 1, characterized in that The pore size of the non-woven gauze mesh is 2 mm or 1 mm.
9. A life-extending Pt-based nanofiber catalytic material obtained by the preparation method according to any one of claims 1 to 8.
10. Use of the life-extending Pt-based nanofiber catalytic material according to claim 9 in a thermal catalytic reaction, specifically use of the Pt-based supported nanocatalyst in a direct dehydrogenation reaction of propane.