High-stability platinum catalyst with self-driven redispersion characteristic as well as preparation method and application of high-stability platinum catalyst

Abstract

The invention provides a high-stability platinum catalyst with a self-driven redispersion characteristic as well as a preparation method and application of the high-stability platinum catalyst. According to the catalyst, a silanol-rich nest-based molecular sieve (such as a pure silicon molecular sieve S-1) is used as a carrier, and a transition metal oxide and an active component Pt are loaded in sequence; the transition metal is selected from at least one of Ga, In, Zn, Cu, Co and Ge, the loading capacity of the transition metal in the catalyst is 0.2-5 wt%, and the loading capacity of Pt is 0.1-1 wt%. Self-driven redispersion of the transition metal oxide is realized through the silanol-rich nest-based molecular sieve, so that a coordinated unsaturated metal oxide surface layer is constructed and used for anchoring Pt species, and a Pt-metal oxide-carrier three-dimensional stable structure is formed. According to the method, a high-dispersion coordination unsaturated metal oxide surface layer is successfully constructed, the problems that Pt on a traditional carrier is difficult to highly disperse and is easy to sinter in a high-temperature reaction are effectively solved, and the catalyst shows high activity and high stability in a low-carbon alkane dehydrogenation reaction and has an important industrial application prospect.

Description

Technical Field

[0001] This invention belongs to the field of thermocatalysis technology, specifically relating to a highly stable platinum catalyst with self-driven redispersibility, its preparation method, and its application. Background Technology

[0002] Propylene is an important chemical raw material, crucial for the production of various chemical products. However, with the continuous consumption of fossil fuels, traditional methods of producing propylene from coal or oil can no longer meet the ever-increasing demand for propylene. Chem. Soc. Rev. 2021, 50 (5), 3315-3354). Therefore, direct propane dehydrogenation (PDH) technology has attracted much attention as a dedicated method for propylene production. Related industrial PDH processes have been widely used globally. For example, the UOP Oleflex™ process uses a Pt-based catalyst in a moving bed reaction-regeneration system to achieve direct propane dehydrogenation (CN115121185B; CN113608430A) as one of the representative routes. As a direct method for propylene production, it has the advantage of high atom utilization, and the large-scale development of shale gas globally provides it with sufficient raw materials. Chemical Society Reviews 2021, 50 (20), 11503-11529). Given that it is an endothermic reaction constrained by thermodynamic equilibrium, a relatively high conversion rate can only be obtained at high temperatures ( Rev. Chem. Eng. 2015, 31 (5), 413-436). Currently, Pt is the most commonly used catalyst in PDH reactions. Although Pt has excellent dehydrogenation performance, it is very prone to sintering and agglomeration at high temperatures, and the size of Pt particles is a key factor affecting catalyst performance. Large Pt particles not only tend to cause cracking reactions and deep dehydrogenation, but also reduce the utilization efficiency of Pt atoms because the Pt inside the particles cannot play a catalytic role. Chemical reviews 2014, 114 (20), 10613-10653; Chemical Society Reviews 2021, 50 (9), 5590-5630; ACS Catal. 2020, 10 (21), 12932-12942). Industrially, Pt-Sn / Pt-Ga composites or alloys are often formed with additives such as Sn and Ga to improve selectivity and stability (CN111992207B; CN116408074B). However, at high temperatures, additives are prone to loss or phase transformations in the alloy, which still leads to deactivation of this type of catalyst. Summary of the Invention

[0003] This invention addresses the common technical problems of supported Pt-based catalysts, such as low dispersion, insufficient exposure of active sites, and easy sintering and agglomeration at high temperatures, by providing a highly stable platinum catalyst with self-driven redispersion characteristics, its preparation method, and its application.

[0004] To address the aforementioned technical challenges, this invention utilizes the interaction between metal oxides and S-1 to form a highly dispersed, coordinated, unsaturated metal oxide pseudo-surface layer on S-1, serving as anchoring sites for Pt. In-situ migration technology is employed to achieve high dispersion of Pt. Furthermore, it exhibits excellent catalytic performance and long-term stability in the direct propane dehydrogenation (PDH) reaction, providing crucial material support for the industrial application of PDH technology.

[0005] The technical solution adopted in this invention is as follows: A highly stable platinum catalyst with self-driven redispersion properties. The catalyst uses a silanol-rich nested molecular sieve (such as pure silica molecular sieve S-1) as a support, sequentially loading transition metal oxides and the active component Pt; the transition metal is selected from at least one of Ga, In, Zn, Cu, Co, and Ge, with a loading of 0.2–5 wt% in the catalyst, and the loading of Pt is 0.1–1 wt%.

[0006] The method for preparing a highly stable platinum catalyst with self-driven redispersibility includes the following steps: S1: Dissolve tetrapropylammonium hydroxide and tetraethyl orthosilicate in water; S2: Stir continuously at 10-35℃ for 4-8 hours; S3: Add any one of the transition metal oxides or their precursor salts to the product obtained in step S2; S4: Add chloroplatinic acid hexahydrate to the product obtained in S3; S5: Place the product obtained in S4 into a high-pressure reactor and heat it to 160-180 ℃ for 0.1-72 h; S6: Separate the product obtained in S5 into solid and liquid phases, discard the liquid and obtain a white solid powder; S7: Grind the white solid powder; S8: The product obtained in S7 was heated to 600-700 ℃ under a reducing atmosphere and held for 2-5 h to obtain a black powder, denoted as Pt-MO. x / S-1, M is Ga, In, Zn, Cu, Co or Ge.

[0007] Application of a highly stable platinum catalyst with self-driven redispersibility in the direct dehydrogenation reaction of low-carbon alkanes.

[0008] Furthermore, the low-carbon alkane is propane. The catalyst is packed in a fixed-bed reactor, and the reaction gas is a C3H8-H2-Ar mixture with a volume ratio of 5:(1-2):(1-38). At the catalytic reaction temperature, the reaction gas is introduced into the catalyst bed to carry out the catalytic dehydrogenation reaction of propane. The catalytic reaction temperature is 520-600 °C, the reaction pressure is atmospheric pressure, and the reaction space velocity is 10000-40000 mL / (gcat ·h).

[0009] Preferably, the catalytic reaction temperature is 520-550 °C and the reaction space velocity is 15000-20000 mL / (gcat ·h).

[0010] Compared with the prior art, the beneficial effects achieved by the present invention are: (1) This invention innovatively overcomes the key technical challenges of low dispersion, poor thermal stability, and insufficient catalytic activity of existing Pt-based supported catalysts, and successfully develops a supported Pt catalyst with high dispersion characteristics. This catalyst exhibits excellent catalytic performance (propane conversion up to 40%, propylene selectivity up to 99%) and long-term stability (stable operation at 550 °C for >200 h) in the propane dehydrogenation (PDH) reaction, providing a breakthrough solution for the industrial application of Pt-based catalytic materials and having significant value for promoting the development of efficient conversion technology for low-carbon alkanes.

[0011] (2) This invention patent proposes a novel strategy for designing highly stable catalysts based on the strengthening of interfacial bonding of transition metal oxides. By constructing a three-dimensional stabilization structure of "Pt-metal oxide surface layer-support", the problem of weak interaction between metal and support in traditional Pt-based supported catalysts is solved. Specifically, the interaction between metal oxides (Zn, Ga, In, Cu, Co, Ge, etc.) and hydroxyl groups on the S-1 surface forms high-density anchoring sites on the S-1 surface, and the chemical anchoring of Pt is achieved through the Pt-OMS-1 (M = Ga, In, Cu, Co, Ge, etc.) bonding structure, making it difficult for Pt to sinter and agglomerate at high temperatures. This catalyst has excellent stability. Attached Figure Description

[0012] Figure 1 This is a scanning electron microscope image of the S-1 carrier; Figure 2 This is the X-ray powder diffraction pattern of the S-1 support; Figure 3 The reaction results of the catalyst in Comparative Example 1 at a catalytic reaction temperature of 550 °C are shown. Figure 4 This is a graph showing the stability test results of the highly stable platinum catalyst with self-driven redispersion characteristics in Example 1; Figure 5The image shows an electron microscope (EM) image of the Pt-ZnO / S-1- impregnated catalyst in Comparative Example 2. Figure 6 This is an electron microscope image of the Pt-ZnO / S-1 catalyst in Example 6. Detailed Implementation

[0013] It should be noted that the embodiments described herein are merely exemplary implementations of the technical solutions of the present invention and are not an exhaustive enumeration of the scope of protection. The detailed description of the embodiments in this section is intended to help understand the core principles and implementation methods of the present invention, and is not intended to limit the scope of the claims. It should be understood that, based on the technical concepts disclosed in this specification, any technical solution obtained by those skilled in the art through equivalent substitution, conventional experimentation, or technical extension without creative effort should be considered to fall within the scope of protection of the present invention.

[0014] In the following examples, a fixed-bed reactor and an online gas chromatography system were used for real-time detection (fixed-bed model and manufacturer: Betterwork Xiamen Baidewo Intelligent Technology Co., Ltd.; online chromatograph model and manufacturer: GC2060 Shanghai Ruimin Instrument Co., Ltd.).

[0015] The S-1 carrier used in this embodiment of the invention has the following scanning electron microscope image: Figure 1 As shown, its morphology is uniformly spherical, and its X-ray powder diffraction (XRD) pattern is as follows. Figure 2 As shown, it has a distinct molecular sieve crystal structure.

[0016] Example 1 1. Preparation of different metal oxide catalysts, including the following steps: a) Dissolve 4 g of tetrapropylammonium hydroxide and 16 g of tetraethyl orthosilicate in 46 g of water; b) Stir continuously at 25 °C for 6 h; c) Add 95 mg of GaO to the product obtained in step b); d) Add 32 mg of chloroplatinic acid hexahydrate to the product obtained in step c); e) Place the product obtained in step d) into a high-pressure reactor and heat it to 170 °C for 2 h; f) Separate the product obtained in step e) into a solid-liquid phase, discard the liquid to obtain a white solid powder; g) Grind the white solid powder; h) The product obtained in step g) is heated to 600 °C under a reducing atmosphere and held for 2 h to obtain a black powder, which is the final catalyst Pt-GaO / S-1.

[0017] 2. Propane oxidative dehydrogenation activity test The catalytic performance was evaluated using a fixed-bed reactor (quartz tube inner diameter 6 mm). 100 mg of catalyst was mixed with an equal mass of quartz sand (60-80 mesh) and packed into the middle of the reaction tube. The temperature was raised to the catalytic reaction temperature. The reaction gas composition was C3H8:H2:Ar (volume ratio = 5:2:38), with a total flow rate of 45 mL / min, where Ar was used as a dilution gas. The mass hourly space velocity (WHSV) was 27000 mL / (g) cat • h). The reaction products were monitored in real time by online gas chromatography (equipped with TCD and FID detectors). The reaction results of the catalyst at a catalytic reaction temperature of 550 °C according to the above catalytic reaction process are shown in Table 1. The conversion and selectivity test results within 100 h are as follows: Figure 4 As shown.

[0018] Example 2 1. Preparation of different metal oxide catalysts, including the following steps: a) Dissolve 4 g of tetrapropylammonium hydroxide and 16 g of tetraethyl orthosilicate in 46 g of water; b) Stir continuously at 25 °C for 6 h; c) Add 95 mg of Co3O4 to the product obtained in step b); d) Add 32 mg of chloroplatinic acid hexahydrate to the product obtained in step c); e) Place the product obtained in step d) into a high-pressure reactor and heat it to 170 °C for 2 h; f) Separate the product obtained in step e) into a solid-liquid phase, discard the liquid to obtain a white solid powder; g) Grind the white solid powder; h) The product obtained in step g) is heated to 600 °C under a reducing atmosphere and held for 2 h to obtain a black powder, which is the final catalyst Pt-Co3O4 / S-1.

[0019] 2. Propane oxidative dehydrogenation activity test The catalytic performance was evaluated using a fixed-bed reactor (quartz tube inner diameter 6 mm). 100 mg of catalyst was mixed with an equal mass of quartz sand (60-80 mesh) and packed into the middle of the reaction tube. The temperature was raised to the catalytic reaction temperature. The reaction gas composition was C3H8:H2:Ar (volume ratio = 5:2:38), with a total flow rate of 45 mL / min, where Ar was used as a dilution gas. The mass hourly space velocity (WHSV) was 27000 mL / (g) cat •h). The reaction products were monitored in real time by online gas chromatography (equipped with TCD and FID detectors). The reaction results of the catalyst at a catalytic reaction temperature of 550 °C according to the above catalytic reaction process are shown in Table 1.

[0020] Example 3 1. Preparation of different metal oxide catalysts, including the following steps: a) Dissolve 4 g of tetrapropylammonium hydroxide and 16 g of tetraethyl orthosilicate in 46 g of water; b) Stir continuously at 25 °C for 6 h; c) Add 95 mg of CuO to the product obtained in step b); d) Add 32 mg of chloroplatinic acid hexahydrate to the product obtained in step c); e) Place the product obtained in step d) into a high-pressure reactor and heat it to 170 °C for 2 h; f) Separate the product obtained in step e) into a solid-liquid phase, discard the liquid to obtain a white solid powder; g) Grind the white solid powder; h) The product obtained in step g) is heated to 600 °C under a reducing atmosphere and held for 2 h to obtain a black powder, which is the final catalyst Pt-CuO / S-1.

[0021] 2. Propane oxidative dehydrogenation activity test The catalytic performance was evaluated using a fixed-bed reactor (quartz tube inner diameter 6 mm). 100 mg of catalyst was mixed with an equal mass of quartz sand (60-80 mesh) and packed into the middle of the reaction tube. The temperature was raised to the catalytic reaction temperature. The reaction gas composition was C3H8:H2:Ar (volume ratio = 5:2:38), with a total flow rate of 45 mL / min, where Ar was used as a dilution gas. The mass hourly space velocity (WHSV) was 27000 mL / (g) cat •h). The reaction products were monitored in real time by online gas chromatography (equipped with TCD and FID detectors). The reaction results of the catalyst at a catalytic reaction temperature of 550 °C according to the above catalytic reaction process are shown in Table 1.

[0022] Example 4 1. Preparation of different metal oxide catalysts, including the following steps: a) Dissolve 4 g of tetrapropylammonium hydroxide and 16 g of tetraethyl orthosilicate in 46 g of water; b) Stir continuously at 25 °C for 6 h; c) Add 95 mg of NbO to the product obtained in step b); d) Add 32 mg of chloroplatinic acid hexahydrate to the product obtained in step c); e) Place the product obtained in step d) into a high-pressure reactor and heat to 170 °C for 2 h. f) Separate the product obtained in step e) into a solid-liquid phase, discard the liquid to obtain a white solid powder.

[0023] g) Grind the white solid powder h) The product obtained in step g) is heated to 600 °C under a reducing atmosphere and held for 2 h to obtain a black powder, which is the final catalyst Pt-NbO / S-1.

[0024] 2. Propane oxidative dehydrogenation activity test The catalytic performance was evaluated using a fixed-bed reactor (quartz tube inner diameter 6 mm). 100 mg of catalyst was mixed with an equal mass of quartz sand (60-80 mesh) and packed into the middle of the reaction tube. The temperature was raised to the catalytic reaction temperature. The reaction gas composition was C3H8:H2:Ar (volume ratio = 5:2:38), with a total flow rate of 45 mL / min, where Ar was used as a dilution gas. The mass hourly space velocity (WHSV) was 27000 mL / (g) cat •h). The reaction products were monitored in real time by online gas chromatography (equipped with TCD and FID detectors). The reaction results of the catalyst at a catalytic reaction temperature of 550 °C according to the above catalytic reaction process are shown in Table 1.

[0025] Example 5 1. Preparation of different metal oxide catalysts, including the following steps: a) Dissolve 4 g of tetrapropylammonium hydroxide and 16 g of tetraethyl orthosilicate in 46 g of water; b) Stir continuously at 25 °C for 6 h; c) Add 95 mg of InO to the product obtained in step b); d) Add 32 mg of chloroplatinic acid hexahydrate to the product obtained in step c); e) Place the product obtained in step d) into a high-pressure reactor and heat it to 170 °C for 2 h; f) Separate the product obtained in step e) into a solid-liquid phase, discard the liquid to obtain a white solid powder; g) Grind the white solid powder; h) The product obtained in step g) is heated to 600 °C under a reducing atmosphere and held for 2 h to obtain a black powder, which is the final catalyst Pt-InO / S-1.

[0026] 2. Propane oxidative dehydrogenation activity test The catalytic performance was evaluated using a fixed-bed reactor (quartz tube inner diameter 6 mm). 100 mg of catalyst was mixed with an equal mass of quartz sand (60-80 mesh) and packed into the middle of the reaction tube. The temperature was raised to the catalytic reaction temperature. The reaction gas composition was C3H8:H2:Ar (volume ratio = 5:2:38), with a total flow rate of 45 mL / min, where Ar was used as a dilution gas. The mass hourly space velocity (WHSV) was 27000 mL / (g) cat •h). The reaction products were monitored in real time by online gas chromatography (equipped with TCD and FID detectors). The reaction results of the catalyst at a catalytic reaction temperature of 550 °C according to the above catalytic reaction process are shown in Table 1.

[0027] Example 6 1. Preparation of different metal oxide catalysts, including the following steps: a) Dissolve 4 g of tetrapropylammonium hydroxide and 16 g of tetraethyl orthosilicate in 46 g of water; b) Stir continuously at 25 °C for 6 h; c) Add 95 mg of ZnO to the product obtained in step b); d) Add 32 mg of chloroplatinic acid hexahydrate to the product obtained in step c); e) Place the product obtained in step d) into a high-pressure reactor and heat it to 170 °C for 2 h; f) Separate the product obtained in step e) into a solid-liquid phase, discard the liquid to obtain a white solid powder; g) Grind the white solid powder; h) The product obtained in step g) is heated to 600 °C under a reducing atmosphere and held for 2 h to obtain a black powder, which is the final catalyst Pt-ZnO / S-1.

[0028] 2. Propane oxidative dehydrogenation activity test The catalytic performance was evaluated using a fixed-bed reactor (quartz tube inner diameter 6 mm). 100 mg of catalyst was mixed with an equal mass of quartz sand (60-80 mesh) and packed into the middle of the reaction tube. The temperature was raised to the catalytic reaction temperature. The reaction gas composition was C3H8:H2:Ar (volume ratio = 5:2:38), with a total flow rate of 45 mL / min, where Ar was used as a dilution gas. The mass hourly space velocity (WHSV) was 27000 mL / (g) cat •h). The reaction products were monitored in real time by online gas chromatography (equipped with TCD and FID detectors). The reaction results of the catalyst at a catalytic reaction temperature of 550 °C according to the above catalytic reaction process are shown in Table 1.

[0029] Example 7 1. Preparation of different metal oxide catalysts, including the following steps: a) Dissolve 4 g of tetrapropylammonium hydroxide and 16 g of tetraethyl orthosilicate in 46 g of water; b) Stir continuously at 25 °C for 6 h; c) Add 190 mg of ZnO to the product obtained in step b); d) Add 32 mg of chloroplatinic acid hexahydrate to the product obtained in step c); e) Place the product obtained in step d) into a high-pressure reactor and heat it to 170 °C for 2 h; f) Separate the product obtained in step e) into a solid-liquid phase, discard the liquid to obtain a white solid powder; g) Grind the white solid powder; h) The product obtained in step g) is heated to 600 °C under a reducing atmosphere and held for 2 h to obtain a black powder, which is the final catalyst Pt-ZnO / S-1.

[0030] 2. Propane oxidative dehydrogenation activity test The catalytic performance was evaluated using a fixed-bed reactor (quartz tube inner diameter 6 mm). 100 mg of catalyst was mixed with an equal mass of quartz sand (60-80 mesh) and packed into the middle of the reaction tube. The temperature was raised to the catalytic reaction temperature. The reaction gas composition was C3H8:H2:Ar (volume ratio = 5:2:38), with a total flow rate of 45 mL / min, where Ar was used as a dilution gas. The mass hourly space velocity (WHSV) was 27000 mL / (g) cat •h). The reaction products were monitored in real time by online gas chromatography (equipped with TCD and FID detectors). The reaction results of the catalyst at a catalytic reaction temperature of 550 °C according to the above catalytic reaction process are shown in Table 1.

[0031] Example 8 1. Preparation of different metal oxide catalysts, including the following steps: a) Dissolve 4 g of tetrapropylammonium hydroxide and 16 g of tetraethyl orthosilicate in 46 g of water; b) Stir continuously at 25 °C for 6 h; c) Add 28 mg of ZnO to the product obtained in step b); d) Add 32 mg of chloroplatinic acid hexahydrate to the product obtained in step c); e) Place the product obtained in step d) into a high-pressure reactor and heat it to 170 °C for 2 h; f) Separate the product obtained in step e) into a solid-liquid phase, discard the liquid to obtain a white solid powder; g) Grind the white solid powder; h) The product obtained in step g) is heated to 600 °C under a reducing atmosphere and held for 2 h to obtain a black powder, which is the final catalyst Pt-ZnO / S-1.

[0032] 2. Propane oxidative dehydrogenation activity test The catalytic performance was evaluated using a fixed-bed reactor (quartz tube inner diameter 6 mm). 100 mg of catalyst was mixed with an equal mass of quartz sand (60-80 mesh) and packed into the middle of the reaction tube. The temperature was raised to the catalytic reaction temperature. The reaction gas composition was C3H8:H2:Ar (volume ratio = 5:2:38), with a total flow rate of 45 mL / min, where Ar was used as a dilution gas. The mass hourly space velocity (WHSV) was 27000 mL / (g) cat •h). The reaction products were monitored in real time by online gas chromatography (equipped with TCD and FID detectors). The reaction results of the catalyst at a catalytic reaction temperature of 550 °C according to the above catalytic reaction process are shown in Table 1.

[0033] Comparative Example 1 1. Preparation of different metal oxide catalysts, including the following steps: a) Dissolve 4 g of tetrapropylammonium hydroxide and 16 g of tetraethyl orthosilicate in 46 g of water; b) Stir continuously at 25 °C for 6 h; c) Add 32 mg of chloroplatinic acid hexahydrate to the product obtained in step c); d) Place the product obtained in step d) into a high-pressure reactor and heat it to 170 °C for 2 h; e) Separate the product obtained in step e) into a solid-liquid phase and discard the liquid to obtain a white solid powder; f) Grind the white solid powder; g) The product obtained in step g) is heated to 600 °C under a reducing atmosphere and held for 2 h to obtain a black powder, which is the final catalyst Pt / S-1.

[0034] 2. Propane oxidative dehydrogenation activity test The catalytic performance was evaluated using a fixed-bed reactor (quartz tube inner diameter 6 mm). 100 mg of catalyst was mixed with an equal mass of quartz sand (60-80 mesh) and packed into the middle of the reaction tube. The temperature was raised to the catalytic reaction temperature. The reaction gas composition was C3H8:H2:Ar (volume ratio = 5:2:38), with a total flow rate of 45 mL / min, where Ar was used as a dilution gas. The mass hourly space velocity (WHSV) was 27000 mL / (g) cat•h). The reaction products were monitored in real time by online gas chromatography (equipped with TCD and FID detectors). The reaction results of the catalyst at a catalytic reaction temperature of 550 °C according to the above catalytic reaction procedure are shown in [reference]. Figure 3 As shown in Table 1.

[0035] The results in Table 1 show that, compared to catalysts without added metal oxides, catalysts with various added metal oxides achieved significantly improved selectivity and stability at almost the same initial conversion rate. Furthermore, selectivity and stability continued to increase with the addition of metal oxides. However, the initial conversion rate decreased when a certain threshold was exceeded.

[0036] Comparative Example 2 The Pt-ZnO / S-1-impregnated catalyst with the same content as in Example 6 was prepared using a conventional impregnation method, comprising the following steps: a) Dissolve 32 mg of chloroplatinic acid hexahydrate and zinc chloride with the same Zn content in water and immerse it on S-1; b) Drying to remove moisture; c) The temperature was raised to 600 °C under a reducing atmosphere and held for 2 h to obtain a black powder, which is the final catalyst Pt-ZnO / S-1-impregnated.

[0037] Figure 6 The particle size of the metal particles in it is significantly smaller than that in the past. Figure 5 The size of the metal particles indicates that the metal dispersion of the catalyst prepared by the method provided in this invention is greater than that of the conventional impregnation method.

[0038] Table 1. Summary of catalytic performance of catalysts prepared from different metal precursors Example Metal precursor Transition metal content (wt%) Hydrothermal time (h) <![CDATA[Reaction gas ratio (C3H8:H2:Ar)]]> Reaction temperature (°C) Initial conversion rate (%) Initial selectivity (%) Reaction time (h) 1 GaO 1.9 2 5:2:38 550 64 83 4 2 <![CDATA[Co3O4]]> 1.9 2 5:2:38 550 73 40 4 3 CuO 1.9 2 5:2:38 550 63 81 4 4 NbO 1.9 2 5:2:38 550 56 81 4 5 InO 1.9 2 5:2:38 550 59 95 4 6 ZnO 1.9 2 5:2:38 550 61 99 4 7 ZnO 3.8 2 5:2:38 550 47 98 4 8 ZnO 0.56 2 5:2:38 550 62 95 4 Comparative Example 1 none 0 2 5:2:38 550 58 79 4 .

Claims

1. A highly stable platinum catalyst with self-driven redispersion properties, characterized in that, Using a silanol-rich nested β-based molecular sieve as a support, transition metal oxides and active component Pt are sequentially loaded. The active site Pt is loaded in the form of single atoms on the surface layer of the unsaturated metal oxide formed by the coordination unsaturated transition metal oxide on the support. The transition metal is selected from at least one of Ga, In, Zn, Cu, Co, and Ge, and its loading in the catalyst is 0.2–5 wt%, while the loading of Pt is 0.1–1 wt%.

2. A method for preparing a highly stable platinum catalyst with self-driven redispersibility as described in claim 1, characterized in that, Includes the following steps: S1: Dissolve tetrapropylammonium hydroxide and tetraethyl orthosilicate in water; S2: Stir continuously at 10-35℃ for 4-8 hours; S3: Add the transition metal oxide to the product obtained in step S2; S4: Add chloroplatinic acid hexahydrate to the product obtained in step S3; S5: Place the product obtained in step S4 into a high-pressure reactor and heat it for reaction; S6: Separate the product obtained in step S5 into solid and liquid phases, discard the liquid to obtain a white solid powder; S7: Grind the white solid powder; S8: The product obtained in step S7 is heated under a reducing atmosphere to produce a black powder.

3. The method for preparing a highly stable platinum catalyst with self-driven redispersibility as described in claim 2, characterized in that, In step S1, the mass ratio of tetrapropylammonium hydroxide to tetraethyl orthosilicate is 1:4-12.

4. The method for preparing a highly stable platinum catalyst with self-driven redispersibility as described in claim 2, characterized in that, In step S5, heat to 160-180 ℃ and maintain for 0.1-72 hours.

5. A method for preparing a highly stable platinum catalyst with self-driven redispersibility as described in claim 2, characterized in that, In step S8, the temperature is raised to 600-700 ℃ and maintained for 2-5 h.

6. The application of a highly stable platinum catalyst with self-driven redispersibility as described in claim 1 in the catalytic direct dehydrogenation reaction of low-carbon alkanes.

7. The application as described in claim 6, characterized in that, The low-carbon alkane is propane. The catalyst is packed in a fixed-bed reactor. The reaction gas is a C3H8-H2-Ar mixture with a volume ratio of 5:1-2:

138. The reaction gas is introduced into the catalyst bed at the catalytic reaction temperature of 520-600 °C, the reaction pressure is atmospheric pressure, and the reaction space velocity is 10000-40000 mL / (gcat ·h).

8. The application as described in claim 7, characterized in that, The reaction temperature is 520-550 ℃, and the reaction space velocity is 15000-20000 mL / (gcat ·h).

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