Monatomic alloy catalyst for direct dehydrogenation of propane and method for preparing the same

Abstract

The application discloses a monatomic alloy catalyst for direct dehydrogenation of propane and a preparation method and application thereof, and has a chemical formula of Pt1FeSn / x-Al2O3 (x = alpha, theta, delta, gamma, kappa); the carrier is one of Al2O3 with crystal forms of alpha, theta, delta, gamma and kappa; the Al2O3 carrier with different crystal forms is obtained by calcining the pseudo-water aluminum stone precursor in air at different temperatures, and then Sn, Fe and Pt are sequentially loaded on the surface of the carrier by impregnation and calcination, so that the monatomic alloy catalyst is prepared; the monatomic alloy catalyst is used in the direct dehydrogenation reaction of propane, high yield and stable yield of propylene are realized, and the propylene yield of the propane dehydrogenation and the overall stability of the catalytic system are remarkably improved; and the application belongs to the field of petroleum chemical industry.

Description

Technical Field

[0001] This invention relates to the field of petrochemicals, specifically to a single-atom alloy catalyst for the direct dehydrogenation of propane to propylene. The invention also relates to the preparation method and application of this catalyst. Background Technology

[0002] Propylene, as a crucial raw material in the chemical industry, has seen its demand increase rapidly in recent years. To meet this growing demand, improving propylene production capacity and optimizing related reaction catalysts are of significant economic and scientific value. Conventional propylene production processes involve fluid catalytic cracking and steam cracking of naphtha and light diesel oil. However, with the rapid depletion of fossil fuels, traditional propylene production methods can no longer meet the increasing demand. Therefore, developing efficient propylene production technologies is of great scientific and economic importance. In recent years, propylene production technologies have seen extensive development, such as propane dehydrogenation (PDH), methanol-to-olefins (MTO), and Fischer-Tropsch to olefins (FTO). Notably, compared to other technologies, PDH technology boasts advantages such as a simple reaction process, high product yield, small plant footprint, and relatively low investment. Furthermore, due to the high purity and large yield of hydrogen produced as a byproduct in PDH technology, according to TrendBank's forecast, with the development of hydrogen energy applications and the construction and commissioning of propane dehydrogenation projects nationwide, PDH will become the mainstay of domestic hydrogen energy supply. Furthermore, with the further development of fracturing technology, the large-scale production of propane-rich shale gas condensate can be achieved, further reducing the price of propane, the feedstock for PDH technology. Therefore, in recent years, PDH technology has been considered one of the most promising methods for propylene production.

[0003] Industrially, catalysts used for the direct dehydrogenation of propane are mainly Pt-based and Cr-based catalysts. For example, UOP's Oleflex process uses a PtSn / Al2O3 catalyst, and Lummus's Catofin process uses a Cr2O3 / Al2O3 catalyst. While the noble metal Pt exhibits high activity and is environmentally friendly in propane dehydrogenation, its high price increases production costs. Furthermore, under harsh high-temperature and low-pressure production conditions, Pt is prone to sintering and carbon buildup, leading to reduced activity. The addition of auxiliary metals can effectively modulate the electronic structure environment surrounding the active component, thereby improving catalyst activity and stability. Therefore, applying newly designed single-atom alloy catalysts to the direct dehydrogenation of propane to propylene holds promise for solving these current problems. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide a method for preparing a single-atom alloy catalyst for the direct dehydrogenation of propane to propylene. The catalyst's active center comprises three metals: one metal, Pt, exists in single-atom form; one metal, Fe, exists in single-atom form; and one metal, Sn, exists in the form of an alloy substrate.

[0005] To achieve the above objectives, the first technical solution provided by the present invention is as follows:

[0006] A single-atom alloy catalyst for the direct dehydrogenation of propane to propylene, characterized in that the single-atom catalyst has the chemical formula Pt1FeSn / x-Al2O3;

[0007] Among them, Pt forms a single-atom alloy with the auxiliary metals Fe and Sn in the form of a single atom and is supported on an Al2O3 support, accounting for one to two parts per thousand of the single-atom alloy catalyst by mass fraction.

[0008] The additive metal Fe accounts for 0.07% to 0.09% of the mass fraction of the single-atom alloy catalyst and exists in the trimetallic alloy in single-atom form.

[0009] The mass fraction of the additive metal Sn accounts for one to two-thousandths of the mass of the single-atom alloy catalyst.

[0010] The x-Al2O3 is an Al2O3 support with five different crystal forms: α, θ, δ, γ, and κ.

[0011] The second technical solution provided by this invention is as follows:

[0012] The method for preparing the above-mentioned single-atom alloy catalyst for the direct dehydrogenation of propane to propylene includes the following steps in sequence:

[0013] 1) Five different Al2O3 supports were obtained by calcining the pseudohydrophilic boehmite precursor at 650, 800, 900, 1050 and 1150 °C, respectively.

[0014] 2) Slowly add an equal volume of Sn metal precursor and dilute hydrochloric acid mixture to the carrier prepared in step 1), let it stand at room temperature for 2 hours, freeze dry overnight, and then calcine at 560°C for 2 hours.

[0015] 3) Slowly add an equal volume of Fe metal precursor and dilute hydrochloric acid mixed solution to the Sn / x-Al2O3 prepared in step 2), let it stand at room temperature for 2 hours, then vacuum dry it overnight at 60°C, and then calcine it at 560°C for 2 hours.

[0016] 4) Slowly add an equal volume of Pt metal precursor and dilute hydrochloric acid mixed solution to FeSn / x-Al2O3 prepared in step 3), let it stand at room temperature for 2 hours, then vacuum dry it overnight at 60°C, and then calcine it at 560°C for 2 hours.

[0017] 5) The PtFeSnO prepared in step 4) x / x-Al2O3 was placed in a 10 mm fixed-bed quartz tube under a hydrogen atmosphere and heated from room temperature to 550 °C at a rate of 10 °C / min and held at that temperature for 1 h. After cooling to room temperature, a Pt1Fe1Sn / x-Al2O3 single-atom alloy catalyst was obtained.

[0018] Preferably, the Sn precursor in step 2) is SnCl2.

[0019] Preferably, the Fe precursor in step 3) is FeCl3.

[0020] Preferably, the Pt precursor in step 4) is HPtCl6.

[0021] Preferably, the hydrogen atmosphere in step 5) is 25% H2, and the equilibrium gas is inert gas N2.

[0022] This invention provides a method for the direct dehydrogenation of propane to propylene, using a fixed-bed quartz tube reactor. The reactor uses a 25% propane mixture with an inert equilibrium gas as the equilibrium gas, with a total gas flow rate of 30-40 ml / min and a mass hourly space velocity (WHSV) of 0.5-10 h⁻¹. -1 The reaction pressure is 0.1 MPa and the reaction temperature is 500-600℃.

[0023] Preferably, the inert gas is argon or nitrogen.

[0024] Compared with the prior art, the technical solution provided by the present invention has the following technical advantages:

[0025] (1) The preparation method of the technical solution provided by the present invention is to dope isolated Pt and Fe atoms onto the Al2O3 support and make the Pt, Fe and Sn single-atom alloy uniformly dispersed on the support, thereby realizing the controllable preparation of single-atom alloy catalysts. It exhibits superior selectivity and stability in the direct dehydrogenation of propane to propylene reaction. The preparation is simple, with low pollution and environmental friendliness.

[0026] (2) The technical solution provided by the present invention improves the catalytic performance of PtSn-based Al2O3 catalyst in propane dehydrogenation by adding trace amounts of Fe.

[0027] (4) The single-atom alloy catalyst prepared in this invention is applied to the direct dehydrogenation of propane to propylene reaction, realizing the efficient utilization of active components and high propylene yield; the obtained propylene content is high and the by-products during the reaction are few. After reactivation with oxygen and hydrogen, the initial propylene yield can reach more than 40%.

[0028] (5) The single-atom alloy catalyst prepared by the present invention is applied to the direct dehydrogenation reaction of propane to propylene, which realizes high utilization of propane raw materials and reduces costs. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the synthesis of Pt1FeSn / x-Al2O3 single-atom alloy catalyst;

[0030] Figure 2 XRD pattern of Pt1FeSn / x-Al2O3 single-atom alloy catalyst;

[0031] Figure 3 AC HAADF-STEM and EDS-mapping images of Pt1FeSn / x-Al2O3 single-atom alloy catalyst;

[0032] Figure 4 The figure shows the catalytic performance of the Pt1FeSn / x-Al2O3 single-atom alloy catalyst in the direct dehydrogenation of propane to propylene reaction. Detailed Implementation

[0033] The technical solution of the present invention will be described in detail below through specific embodiments. However, it should be clearly stated that these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0034] Example 1

[0035] This embodiment provides a Pt1Fe1Sn / γ-Al2O3 single-atom alloy catalyst, which is prepared by the following method:

[0036] 1) Place 2g of pseudo-alumina in a muffle furnace under an air atmosphere and heat it to 1050℃ at a heating rate of 5℃ / min, and hold it at that temperature for 2 hours;

[0037] 2) After cooling the pseudo-hydrated alumina prepared in step 1) to room temperature, a mixed solution of Sn metal precursor and 0.1 mol / L dilute hydrochloric acid, with a volume equal to the saturated water absorption capacity of the support, was slowly added dropwise. After standing at room temperature for 2 hours, it was vacuum freeze-dried overnight (-60℃). Then, it was placed in a muffle furnace and calcined at 560℃ for 2 hours with a heating rate of 5℃ / min. After cooling to room temperature, SnO was obtained. x / θ-Al2O3;

[0038] 3) To the SnO prepared in step 2) x A mixture of Fe metal precursor and 0.1 mol / L dilute hydrochloric acid, with a volume equal to the saturated water absorption capacity of the support, was slowly added dropwise to / θ-Al2O3. After standing at room temperature for 2 hours, it was vacuum dried overnight at 60°C. Then, it was placed in a muffle furnace and calcined at 560°C for 2 hours with a heating rate of 5°C / min. After cooling to room temperature, FeSnO was obtained. x / θ-Al2O3;

[0039] 4) Apply the FeSnO2 prepared in step 3) x A mixture of Pt metal precursor and 0.1 mol / L dilute hydrochloric acid, with a volume equal to the saturated water absorption capacity of the support, was slowly added dropwise to / θ-Al2O3. After standing at room temperature for 2 hours, it was vacuum dried overnight at 60°C. Then, it was placed in a muffle furnace and calcined at 560°C for 2 hours with a heating rate of 5°C / min. After cooling to room temperature, FeSnO was obtained. x / θ-Al2O3.

[0040] 5) The PtFeSnO prepared in step 4) x / θ-Al2O3 was placed in a 10 mm fixed-bed quartz tube under a hydrogen atmosphere and heated from room temperature to 550 °C at a rate of 10 °C / min and held at that temperature for 1 h. After cooling to room temperature, a Pt1Fe1Sn / γ-Al2O3 single-atom alloy catalyst was obtained.

[0041] Figure 1 The diagram shown is a schematic diagram of the synthesis of the single-atom alloy catalyst Pt1Fe1Sn / γ-Al2O3. Figure 2 The image shown is an XRD pattern. Figure 3 The image shown is an AC HAADF-STEM image, which indicates that there are 1-2 nm alloy nanoparticles on the surface of the prepared single-atom alloy catalyst. Figure 4 The EDS-mapping diagram shown indicates that Pt, Fe, and Sn are uniformly dispersed on the θ-Al2O3 surface of the prepared single-atom alloy catalyst.

[0042] Example 2

[0043] This embodiment provides a Pt1Fe1Sn / δ-Al2O3 single-atom alloy catalyst, which is prepared by the following method:

[0044] 1) Place 2g of pseudo-alumina in a muffle furnace under an air atmosphere and heat it to 900℃ at a heating rate of 5℃ / min, and hold it at that temperature for 2 hours;

[0045] 2) After cooling the pseudo-hydrated alumina prepared in step 1) to room temperature, a mixed solution of Sn metal precursor and 0.1 mol / L dilute hydrochloric acid, with a volume equal to the saturated water absorption capacity of the support, was slowly added dropwise. After standing at room temperature for 2 hours, it was vacuum freeze-dried overnight (-60℃). Then, it was placed in a muffle furnace and calcined at 560℃ for 2 hours with a heating rate of 5℃ / min. After cooling to room temperature, SnO was obtained. x / δ-Al2O3;

[0046] 3) Apply the SnO prepared in step 2) x A mixture of Fe metal precursor and 0.1 mol / L dilute hydrochloric acid, with a volume equal to the saturated water absorption capacity of the support, was slowly added dropwise to δ-Al₂O₃. After standing at room temperature for 2 hours, it was vacuum dried overnight at 60°C. Then, it was placed in a muffle furnace and calcined at 560°C for 2 hours with a heating rate of 5°C / min. After cooling to room temperature, FeSnO₂ was obtained. x / δ-Al2O3;

[0047] 4) Apply the FeSnO prepared in step 3) x A mixture of Pt metal precursor and 0.1 mol / L dilute hydrochloric acid, with a volume equal to the saturated water absorption capacity of the support, was slowly added dropwise to δ-Al₂O₃. After standing at room temperature for 2 hours, it was vacuum dried overnight at 60°C. Then, it was placed in a muffle furnace and calcined at 560°C for 2 hours with a heating rate of 5°C / min. After cooling to room temperature, FeSnO₂ was obtained. x / δ-Al2O3;

[0048] 5) The PtFeSnO prepared in step 4) x / δ-Al2O3 was placed in a 10 mm fixed-bed quartz tube under a hydrogen atmosphere and heated from room temperature to 550 °C at a rate of 10 °C / min and held at that temperature for 1 h. After cooling to room temperature, a Pt1Fe1Sn / δ-Al2O3 single-atom alloy catalyst was obtained.

[0049] Figure 1 The diagram shown is a schematic diagram of the synthesis of the single-atom alloy catalyst Pt1Fe1Sn / δ-Al2O3. Figure 2 The image shown is an XRD pattern. Figure 3 The image shown is an AC HAADF-STEM image, which indicates that there are 1-2 nm alloy nanoparticles on the surface of the prepared single-atom alloy catalyst. Figure 4 The EDS-mapping diagram shown indicates that Pt, Fe, and Sn are uniformly dispersed on the surface of the prepared single-atom alloy catalyst on the δ-Al2O3 surface.

[0050] Example 3

[0051] This embodiment provides a Pt1Fe1Sn / α-Al2O3 single-atom alloy catalyst, which is prepared by the following method:

[0052] 1) Place 2g of pseudo-alumina in a muffle furnace under an air atmosphere and heat it to 1150℃ at a heating rate of 5℃ / min, and hold it at that temperature for 4 hours;

[0053] 2) After cooling the pseudo-hydrated alumina prepared in step 1) to room temperature, a mixed solution of Sn metal precursor and 0.1 mol / L dilute hydrochloric acid, with a volume equal to the saturated water absorption capacity of the support, was slowly added dropwise. After standing at room temperature for 2 hours, it was vacuum freeze-dried overnight (-60℃). Then, it was placed in a muffle furnace and calcined at 560℃ for 2 hours with a heating rate of 5℃ / min. After cooling to room temperature, SnO was obtained. x / α-Al2O3;

[0054] 3) To the SnO prepared in step 2) x A mixture of Fe metal precursor and 0.1 mol / L dilute hydrochloric acid, with a volume equal to the saturated water absorption capacity of the support, was slowly added dropwise to α-Al₂O₃. After standing at room temperature for 2 hours, it was vacuum dried overnight at 60°C. Then, it was placed in a muffle furnace and calcined at 560°C for 2 hours with a heating rate of 5°C / min. After cooling to room temperature, FeSnO₂ was obtained. x / α-Al2O3;

[0055] 4) Apply the FeSnO2 prepared in step 3) x A mixture of Pt metal precursor and 0.1 mol / L dilute hydrochloric acid, with a volume equal to the saturated water absorption capacity of the support, was slowly added dropwise to α-Al₂O₃. After standing at room temperature for 2 hours, it was vacuum dried overnight at 60°C. Then, it was placed in a muffle furnace and calcined at 560°C for 2 hours with a heating rate of 5°C / min. After cooling to room temperature, FeSnO₂ was obtained. x / α-Al2O3;

[0056] 5) The PtFeSnO prepared in step 4) x / β-Al₂O₃ was placed in a 10 mm fixed-bed quartz tube under a hydrogen atmosphere and heated from room temperature to 550 °C at a rate of 10 °C / min, and held at that temperature for 1 h. After cooling to room temperature, Pt was obtained. l FelSn / α-Al2O3 single-atom alloy catalyst.

[0057] Figure 1 The diagram shown is a schematic diagram of the synthesis of the single-atom alloy catalyst Pt1Fe1Sn / δ-Al2O3. Figure 2 The image shown is an XRD pattern. Figure 3 The image shown is an AC HAADF-STEM image, which indicates that there are 1-2 nm alloy nanoparticles on the surface of the prepared single-atom alloy catalyst. Figure 4 The EDS-mapping diagram shown indicates that Pt, Fe, and Sn are uniformly dispersed on the surface of the prepared single-atom alloy catalyst on the α-Al2O3 surface.

[0058] Example 4

[0059] This embodiment provides a Pt1Fe1Sn / γ-Al2O3 single-atom alloy catalyst, which is prepared by the following method:

[0060] 1) Place 2g of pseudo-alumina in a muffle furnace under an air atmosphere and heat it to 650℃ at a heating rate of 5℃ / min, and hold it at that temperature for 4 hours.

[0061] 2) After cooling the pseudo-hydrated alumina prepared in step 1) to room temperature, a mixed solution of Sn metal precursor and 0.1 mol / L dilute hydrochloric acid, with a volume equal to the saturated water absorption capacity of the support, was slowly added dropwise. After standing at room temperature for 2 hours, it was vacuum freeze-dried overnight (-60℃). Then, it was placed in a muffle furnace and calcined at 560℃ for 2 hours with a heating rate of 5℃ / min. After cooling to room temperature, SnO was obtained. x / γ-Al2O3.

[0062] 3) To the SnO prepared in step 2) x A mixture of Fe metal precursor and 0.1 mol / L dilute hydrochloric acid, with a volume equal to the saturated water absorption capacity of the support, was slowly added dropwise to γ-Al₂O₃. After standing at room temperature for 2 hours, it was vacuum dried overnight at 60°C. Then, it was placed in a muffle furnace and calcined at 560°C for 2 hours with a heating rate of 5°C / min. After cooling to room temperature, FeSnO₂ was obtained. x / γ-Al2O3.

[0063] 4) Apply the FeSnO2 prepared in step 3) x A mixture of Pt metal precursor and 0.1 mol / L dilute hydrochloric acid, with a volume equal to the saturated water absorption capacity of the support, was slowly added dropwise to γ-Al₂O₃. After standing at room temperature for 2 hours, it was vacuum dried overnight at 60°C. Then, it was placed in a muffle furnace and calcined at 560°C for 2 hours with a heating rate of 5°C / min. After cooling to room temperature, FeSnO₂ was obtained. x / γ-Al2O3.

[0064] 5) The PtFeSnO prepared in step 4) x / γ-Al2O3 was placed in a 10 mm fixed-bed quartz tube under a hydrogen atmosphere and heated from room temperature to 550 °C at a heating rate of 10 °C / min and held at that temperature for 1 h. After cooling to room temperature, Pt1Fe1Sn / a-Al2O3 single-atom alloy catalyst was obtained.

[0065] Figure 1The diagram shown is a schematic diagram of the synthesis of the single-atom alloy catalyst Pt1Fe1Sn / δ-Al2O3. Figure 2 The image shown is an XRD pattern. Figure 3 The image shown is an AC HAADF-STEM image, which indicates that there are 1-2 nm alloy nanoparticles on the surface of the prepared single-atom alloy catalyst. Figure 4 The EDS-mapping diagram shown indicates that Pt, Fe, and Sn are uniformly dispersed on the surface of the prepared single-atom alloy catalyst on the γ-Al2O3 surface.

[0066] Example 5

[0067] This embodiment provides a Pt l The FelSn / κ-Al2O3 single-atom alloy catalyst is prepared by the following method:

[0068] 1) Place 2g of pseudo-alumina in a muffle furnace under an air atmosphere and heat it to 800℃ at a heating rate of 5℃ / min, and hold it at that temperature for 4 hours.

[0069] 2) After cooling the pseudo-hydrated alumina prepared in step 1) to room temperature, a mixed solution of Sn metal precursor and 0.1 mol / L dilute hydrochloric acid, with a volume equal to the saturated water absorption capacity of the support, was slowly added dropwise. After standing at room temperature for 2 hours, it was vacuum freeze-dried overnight (-60℃). Then, it was placed in a muffle furnace and calcined at 560℃ for 2 hours with a heating rate of 5℃ / min. After cooling to room temperature, SnO was obtained. x / κ-Al2O3;

[0070] 3) To the SnO prepared in step 2) x A mixture of Fe metal precursor and 0.1 mol / L dilute hydrochloric acid, with a volume equal to the saturated water absorption capacity of the support, was slowly added dropwise to / κ-Al2O3. After standing at room temperature for 2 hours, it was vacuum dried overnight at 60°C. Then, it was placed in a muffle furnace and calcined at 560°C for 2 hours with a heating rate of 5°C / min. After cooling to room temperature, FeSnO was obtained. x / κ-Al2O3.

[0071] 4) Apply the FeSnO2 prepared in step 3) x A mixture of Pt metal precursor and 0.1 mol / L dilute hydrochloric acid, with a volume equal to the saturated water absorption capacity of the support, was slowly added dropwise to / κ-Al₂O₃. After standing at room temperature for 2 hours, it was vacuum dried overnight at 60 °C. Then, it was placed in a muffle furnace and calcined at 560 °C for 2 hours with a heating rate of 5 °C / min. After cooling to room temperature, FeSnO₂ was obtained. x / κ-Al2O3.

[0072] 5) The PtFeSnO prepared in step 4) x / κ-Al2O3 was placed in a 10 mm fixed-bed quartz tube under a hydrogen atmosphere and heated from room temperature to 550 °C at a rate of 10 °C / min and held at that temperature for 1 h. After cooling to room temperature, a Pt1Fe1Sn / κ-Al2O3 single-atom alloy catalyst was obtained.

[0073] Figure 1 The diagram shown is a schematic diagram of the synthesis of the single-atom alloy catalyst Pt1Fe1Sn / κ-Al2O3. Figure 2 The image shown is an XRD pattern. Figure 3 The image shown is an AC HAADF-STEM image, which indicates that there are 1-2 nm alloy nanoparticles on the surface of the prepared single-atom alloy catalyst. Figure 4 The EDS-mapping diagram shown indicates that Pt, Fe, and Sn are uniformly dispersed on the surface of the prepared single-atom alloy catalyst on the κ-Al2O3 surface.

[0074] Application Cases

[0075] The catalytic performance of the single-atom alloy catalysts prepared in Examples 1-5 above for the direct dehydrogenation of propane to propylene was tested.

[0076] A 10 mL r fixed-bed quartz tube reactor was used. 0.25 g of the single-atom alloy catalyst prepared in Example 1, Example 2, Example 3, Example 4, or Example 5 was mixed with 0.75 g of 20-40 mesh quartz sand. The mixture was heated to 550 °C at a rate of 10 °C / min under a 25% propane / inert gas atmosphere. The total gas flow rate was 30 mL / min, the reaction pressure was 0.1 MPa, and the reaction temperature was 550 °C. The gas was monitored in real-time by gas chromatography to analyze propane conversion, propylene selectivity, and yield. The results showed that after a long reaction time, Pt1Fe1Sn / θ-Al2O3 exhibited good stability and propylene yield, demonstrating a significant reaction advantage. Detailed reaction results are shown in Table 1.

[0077] Table 1

[0078]

[0079] Note: The reaction using the catalyst provided in Example 1 is referred to as reaction 1; the reaction using the catalyst provided in Example 2 is referred to as reaction 2; the reaction using the catalyst provided in Example 3 is referred to as reaction 3; the reaction using the catalyst provided in Example 4 is referred to as reaction 4; and the reaction using the catalyst provided in Example 5 is referred to as reaction 5. In reaction 5, the catalyst surface rapidly deposits carbon in the early stage of the reaction, resulting in a lower initial conversion rate and a lower final conversion rate.

Claims

1. A single-atom alloy catalyst for direct dehydrogenation of propane to propylene, characterized by, The chemical formula of the single-atom alloy catalyst is Pt1Fe1Sn / x-Al2O3; Among them, Pt forms a single-atom alloy with the auxiliary metals Fe and Sn in the form of a single atom and is supported on an Al2O3 support, accounting for one to two parts per thousand of the single-atom alloy catalyst by mass fraction. The additive metal Fe accounts for 0.07% to 0.09% of the mass fraction of the single-atom alloy catalyst and exists in the single-atom alloy catalyst in the form of single atoms. The mass fraction of the additive metal Sn accounts for one to two-thousandths of the mass of the single-atom alloy catalyst. The x-Al2O3 is an Al2O3 support with θ crystal form; The method for preparing the single-atom alloy catalyst for the direct dehydrogenation of propane to propylene comprises the following steps in sequence: 1) Calcine the pseudohydrate boehmite at 1050℃ to obtain an Al2O3 support with θ crystal form; 2) Slowly add a mixed solution of Sn metal precursor and dilute hydrochloric acid, equal in volume to the saturated water absorption of the support, to the support prepared in step 1). After standing at room temperature for 2 hours, freeze dry overnight, and then calcine at 560°C for 2 hours. 3) Add a mixed solution of Fe metal precursor and dilute hydrochloric acid of equal volume to the saturated water absorption of the support to the Sn / x-Al2O3 prepared in step 2), let it stand at room temperature for 2 hours, then vacuum dry it overnight at 60°C, and then calcine it at 560°C for 2 hours. 4) Slowly add a mixed solution of Pt metal precursor and dilute hydrochloric acid of equal volume to the saturated water absorption of the support to the FeSn / x-Al2O3 prepared in step 3). After standing at room temperature for 2 hours, vacuum dry at 60°C overnight, and then calcine at 560°C for 2 hours. 5) The PtFeSnO x The Pt1Fe1Sn / x-Al2O3 single atom alloy catalyst was obtained by raising the temperature of PtFeSnO4 / x-Al2O3 prepared in step 4) from room temperature to 550°C at a temperature raising rate of 10°C / min under hydrogen atmosphere in a 10 mm fixed bed quartz tube and keeping the temperature for 1 h, and then lowering the temperature to room temperature.

2. The single atom alloy catalyst for direct dehydrogenation of propane to propylene according to claim 1, wherein The Sn metal precursor is SnCl2; the Fe metal precursor is FeCl3; and the Pt metal precursor is HPtCl6.

3. The single atom alloy catalyst for direct dehydrogenation of propane to propylene according to claim 1, wherein The concentration of the dilute hydrochloric acid is 0.1 mol / L.

4. The application of the catalyst according to claim 1 in the catalytic direct dehydrogenation reaction of propane to propylene.

5. Use according to claim 4, characterized in that, The application comprises the following steps: using fixed bed quartz tube as reactor, using 25% propane mixed gas as equilibrium gas, total gas flow is 30-40ml / min, mass space velocity is 0.5-10h -1 , reaction pressure is 0.1MPa, reaction temperature is 500-600℃.

6. Use according to claim 5, characterized in that, The balancing gas is argon or nitrogen.

Images