Propane dehydrogenation catalyst, preparation method and application

Abstract

The application discloses a propane dehydrogenation catalyst, a preparation method and application, the propane dehydrogenation catalyst includes carrier and the Pt component, Sn component and alkali metal component supported on the carrier;The carrier is spherical activated carbon;The alkali metal component is selected from potassium and / or sodium. Wherein, the carrier is spherical activated carbon, the spherical activated carbon is 0.4-2.0mm spherical particle, the specific surface area of the spherical activated carbon is 500-2000m 2 / g, the pore volume is 0.55-1.5mL / g, has the micropore of 0.5-1.5nm, 4-10nm mesopore and 50-200nm macropore.The catalyst prepared by the application has higher catalytic activity, propylene selectivity and catalytic stability.

Description

Technical Field

[0001] This application relates to a propane dehydrogenation catalyst, its preparation method, and its application, belonging to the field of catalyst technology. Background Technology

[0002] Propylene is used to produce polypropylene, propylene oxide, butanol, phenol, propylene glycol, acetone, acrylic acid, acrylonitrile, octanol, and isopropanol, making it an important basic chemical raw material and petrochemical intermediate. With the rapid development of my country's economy, domestic demand for propylene is growing rapidly. However, traditional propylene production technologies, such as steam cracking and catalytic cracking, which produce propylene as a byproduct, suffer from problems such as the use of lighter feedstocks and slow production growth. Therefore, propylene produced through traditional processes can no longer meet the demand.

[0003] In recent years, with the large-scale exploitation of shale gas in the United States and natural gas in the Middle East, the technology of propane dehydrogenation to produce propylene has received increasing attention and achieved significant development. This technology has advantages such as a short process, high yield, few byproducts, and low investment cost. Currently, the most widely used propane dehydrogenation processes are UOP's Oleflex process and Lummus's Catofin process, which use Pt and Cr as active catalysts, respectively, and alumina as the support. Alumina is the most commonly used support for propane dehydrogenation catalysts, possessing advantages such as large specific surface area, high thermal stability, high mechanical strength, and the ability to disperse metal active components. However, due to the presence of numerous acidic sites on the alumina surface, side reactions such as hydrogenolysis, isomerization, and coking can be exacerbated, leading to lower propylene selectivity. Adding a certain amount of alkaline metal promoters to the catalyst can, to some extent, suppress the occurrence of side reactions. Examples include US patents US2014275686A1 and US2013072739A1; and Chinese patents CN103990454A, CN104289220A, and CN103787810A. However, propylene selectivity is often still below 92%.

[0004] Compared to alumina, activated carbon has a larger specific surface area and weaker acidity / basicity, which can significantly improve the selectivity of propylene products when used as a propane dehydrogenation catalyst support. For example, CN109745978A discloses a propane dehydrogenation catalyst with Pt-Sn supported on a mesoporous carbon material. CN112403458A discloses a propane dehydrogenation catalyst with Cr supported on a non-metallic carbon material. CN109926038A directly uses waste tea carbon as a propane dehydrogenation catalyst. However, most of these reported carbon-supported catalysts use irregular granular activated carbon such as powdered activated carbon or coconut shell carbon as raw materials, which have problems such as difficulty in molding and low strength, making it difficult to meet the needs of practical industrial applications. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, the present invention provides a platinum-based propane dehydrogenation catalyst supported on spherical activated carbon and its preparation method, which has high propylene selectivity and good stability.

[0006] The purpose of this invention is to prepare spherical activated carbon supports based on spherical polymers and to prepare propane dehydrogenation catalysts with high propylene selectivity.

[0007] According to one aspect of this application, a propane dehydrogenation catalyst is provided, the propane dehydrogenation catalyst comprising a support and a Pt component, a Sn component, and an alkali metal component supported on the support;

[0008] The carrier is spherical activated carbon;

[0009] The alkali metal component is selected from at least one of potassium, sodium, lithium, and cesium.

[0010] Optionally, the spherical activated carbon is spherical particles with a diameter of 0.4 to 2.0 mm.

[0011] Optionally, the spherical activated carbon is selected from any value of 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 1.0 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm, 2.0 mm in diameter, or a range between any two of the above.

[0012] Optionally, the specific surface area of ​​the spherical activated carbon is 500–2000 m². 2 / g, with a pore volume of 0.55–1.5 mL / g.

[0013] Optionally, the specific surface area of ​​the spherical activated carbon is selected from 500 m². 2 / g、800m 2 / g, 1000m 2 / g, 1500m 2 / g、2000m 2 Any value in / g or a range between any two of the above.

[0014] Optionally, the pore volume is selected from any value of 0.55 mL / g, 0.7 mL / g, 0.8 mL / g, 1.0 mL / g, 1.2 mL / g, 1.5 mL / g, or a range between any two of the above.

[0015] Optionally, the spherical activated carbon has micropores with a pore size of 0.5–1.5 nm, mesopores with a pore size of 4–10 nm, and macropores with a pore size of 50–200 nm.

[0016] Optionally, the ratio of micropores, mesopores, and macropores in the spherical activated carbon is 1-10:0.1-5:1.

[0017] Optionally, based on the total weight of the propane dehydrogenation catalyst, the content of the support is 94.1–99.7 wt.%, the content of the Pt component (calculated as Pt element) is 0.1–1.0 wt.%, the content of the Sn component (calculated as Sn element) is 0.05–5.0 wt.%, and the content of the alkali metal component (calculated as alkali metal element) is 0.15–2.0 wt.%.

[0018] Optionally, when the alkali metal component is potassium, the content based on potassium metal element is 0.15 to 1.5 wt.%.

[0019] Optionally, when the alkali metal component is sodium, its content, calculated as sodium metal element, is 1.0 to 2.0 wt.%.

[0020] According to another aspect of this application, a method for preparing the propane dehydrogenation catalyst described above is provided, the method comprising:

[0021] The support was impregnated in a mixture containing Pt component precursor, Sn component precursor and alkali metal component precursor, dried and calcined to obtain the propane dehydrogenation catalyst.

[0022] Optionally, the preparation method of the propane dehydrogenation catalyst includes: impregnating a support in a mixed solution containing a Pt component precursor, a Sn component precursor, and an alkali metal component precursor for 0.5–12 h, followed by drying and calcination under a high-temperature inert atmosphere, wherein the support is spherical activated carbon, the spherical activated carbon being spherical particles of 0.4–2.0 mm, and the specific surface area of ​​the spherical activated carbon being 500–2000 m². 2 The pore volume is 0.55–1.5 mL / g, and it has micropores with a pore size of 0.5–1.5 nm, mesopores with a pore size of 4–10 nm, and macropores with a pore size of 50–200 nm.

[0023] Optionally, the carrier is spherical activated carbon, and the preparation method of the spherical activated carbon includes:

[0024] In an inactive atmosphere, spherical polymers are carbonized and then activated by contact with an activator to obtain spherical activated carbon.

[0025] Optionally, the method for forming the carrier includes the following steps:

[0026] (a) The spherical polymer was subjected to high-temperature carbonization under inert conditions to obtain a spherical carrier precursor;

[0027] (b) The spherical carrier precursor obtained in (a) is contacted with an activator at high temperature to activate it, thereby obtaining a spherical activated carbon carrier.

[0028] Optionally, the method for forming the carrier includes the following steps:

[0029] (a) The spherical polymer was subjected to high-temperature carbonization under inert conditions to obtain a spherical carrier precursor;

[0030] (b) The spherical carrier precursor obtained in (a) is contacted with an activator at high temperature to activate it. After cooling, it is then acid-washed, water-washed and dried in sequence to obtain a spherical activated carbon carrier.

[0031] Optionally, the spherical polymer is selected from at least one of phenolic resin, polystyrene resin, and polypropylene resin.

[0032] Optionally, the activator is selected from at least one of water, carbon dioxide, potassium hydroxide, potassium carbonate, and phosphoric acid.

[0033] Optionally, the inactive atmosphere is selected from at least one of nitrogen, argon, and helium.

[0034] Optionally, the carbonization temperature is 600–1200°C, and the carbonization time is 1–8 hours.

[0035] Optionally, the carbonization temperature is selected from any value of 600℃, 700℃, 750℃, 800℃, 900℃, 1200℃ or a range between any two of the above.

[0036] Optionally, the carbonization time is selected from any value of 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h or a range between any two of the above.

[0037] Optionally, the activation temperature is 500–1100°C, and the activation time is 1–8 hours.

[0038] Optionally, the activation temperature is selected from any value of 500℃, 700℃, 750℃, 800℃, 900℃, 1000℃, 1100℃ or a range between any two of the above.

[0039] Optionally, the activation time is selected from any value of 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h or a range between any two of the above.

[0040] Optionally, the Pt component precursor is selected from chloroplatinic acid and / or platinum acetylacetonate.

[0041] Optionally, the Sn component precursor is selected from at least one of stannous chloride and stannous tetrachloride.

[0042] Optionally, the alkali metal component precursor is selected from at least one of potassium chloride, sodium chloride, lithium chloride, potassium nitrate, sodium nitrate, and cesium chloride.

[0043] Optionally, the amounts of the support, Pt component precursor, Sn component precursor, and alkali metal component precursor are such that, based on the total weight of the prepared propane dehydrogenation catalyst, the content of the support is 94.1–99.7 wt.%, the content of the Pt component (based on Pt elemental content) is 0.1–1.0 wt.%, the content of the Sn component (based on Sn elemental content) is 0.05–5.0 wt.%, and the content of the alkali metal component (based on alkali metal elemental content) is 0.15–2.0 wt.%.

[0044] Optionally, the soaking time is 0.5 to 12 hours.

[0045] Optionally, the drying temperature is 60–130°C, and the drying time is 0.5–6 hours.

[0046] Optionally, the drying temperature is selected from any value of 60℃, 70℃, 75℃, 80℃, 90℃, 100℃, 130℃ or a range between any two of the above.

[0047] Optionally, the drying time is selected from any value of 0.5h, 1h, 2h, 3h, 4h, 5h, 6h or a range between any two of the above.

[0048] Optionally, the calcination temperature is 200–800°C, and the calcination time is 1–8 hours.

[0049] Optionally, the calcination temperature is selected from any value of 200℃, 300℃, 400℃, 500℃, 600℃, 800℃ or a range between any two of the above.

[0050] Optionally, the calcination time is selected from any value of 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h or a range between any two of the above.

[0051] According to another aspect of this application, a method for producing propylene by propane dehydrogenation is provided, the method comprising: performing a dehydrogenation reaction on propane in the presence of a propane dehydrogenation catalyst and hydrogen to prepare propylene;

[0052] The propane dehydrogenation catalyst is selected from the propane dehydrogenation catalysts described above.

[0053] Optionally, the conditions for the dehydrogenation reaction include: a reaction temperature of 450–700 °C, a reaction pressure of 0–0.5 MPa, and a propane weight hourly space velocity of 1–20 h⁻¹. -1The hydrogen-hydrogen molar ratio is 0.25:1 to 10:1.

[0054] The catalyst provided by this invention was evaluated under the following conditions:

[0055] The reaction temperature was 450–700℃, the reaction pressure was 0–0.5 MPa, and the weight hourly space velocity of propane was 1–20 h⁻¹. -1 The hydrogen-to-hydrocarbon molar ratio was 0.25:1 to 10:1. The gaseous products of the reaction were analyzed online using an Agilent 7890 gas chromatograph (HP-Al2O3 / KCl capillary packed column, FID detector).

[0056] The beneficial effects that this application can produce include:

[0057] The catalyst obtained by this invention uses weakly acidic, high-strength spherical activated carbon as a support and loads Pt as the main active component. It has good propylene selectivity and catalytic stability, with a propane conversion rate of up to 43% and a propylene selectivity of up to 98.8%. Attached Figure Description

[0058] Figure 1 This is a graph showing the N2 physical adsorption curve of the spherical activated carbon support prepared in Example 1 of this application.

[0059] Figure 2 This is a pore size distribution diagram of the spherical activated carbon carrier prepared in Example 1 of this application.

[0060] Figure 3 This is a physical image of the catalyst Cat-1 prepared in Example 7 of this application.

[0061] Figure 4 This is a graph showing the change in conversion and selectivity of propane dehydrogenation to propylene catalyzed by the catalyst Cat-1 described in Example 20 of this application over time. The vertical axis represents propane conversion or propylene selectivity, and the horizontal axis represents time, in hours (h). Detailed Implementation

[0062] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0063] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.

[0064] The gaseous products of the reaction were analyzed online using an Agilent 7890 gas chromatograph (HP-Al2O3 / KCl capillary packed column, FID detector).

[0065] In the embodiments of this application, room temperature refers to "25°C".

[0066] In the following experimental examples and comparative examples,

[0067] The conversion rate of propane (%) = (amount of propane used - content of propane in the reaction product) ÷ amount of propane used × 100%;

[0068] propylene selectivity (%) = actual propylene yield ÷ theoretical propylene yield × 100%.

[0069] Example 1: Preparation of spherical activated carbon carrier

[0070] 10g of spherical polystyrene resin was placed in the heating zone of a high-temperature furnace, and nitrogen gas (100mL / min) was introduced. The furnace was heated to 800℃, and the mixture was carbonized at a constant temperature for 2 hours to obtain the spherical carrier precursor. The heating zone temperature was then increased to 900℃, and water vapor was introduced into the heating zone for constant temperature activation for 2 hours. After cooling to room temperature, a spherical activated carbon carrier, designated SAC-1, was obtained. Detailed synthesis parameters are listed in Table 1, and specific surface area, pore volume, pore distribution, and other properties are listed in Table 2. Figure 1 The N2 physisorption curve of the prepared spherical activated carbon support is shown in the figure. Figure 1 As can be seen from the curve, SAC-1 exhibits a type IV adsorption curve and has a large adsorption-desorption hysteresis loop in the high relative pressure range, indicating that the carrier SAC-1 contains micropores, mesopores and macropores.

[0071] Figure 2 The pore size distribution diagram of the prepared spherical activated carbon support is shown below. Figure 2 As can be seen, SAC-1 has micropores of 0.8 nm and mesopores of 6.3 nm.

[0072] Examples 2-3: Preparation of spherical activated carbon carriers

[0073] The process was basically the same as in Example 1, except that the spherical polystyrene resin was replaced with spherical phenolic resin and spherical polyacrylonitrile resin, respectively. All other conditions were exactly the same as in Example 1, and spherical activated carbon carriers were obtained, which were designated as SAC-2 and SAC-3, respectively. The detailed synthesis parameters are listed in Table 1, and the specific surface area, pore volume, pore distribution and other properties are listed in Table 2.

[0074] Example 4: Preparation of spherical activated carbon carrier

[0075] 10g of spherical polystyrene resin was placed in the heating zone of a high-temperature furnace, and nitrogen gas (100mL / min) was introduced. The furnace was heated to 600℃, and the mixture was carbonized at a constant temperature for 8 hours to obtain the spherical carrier precursor. The heating zone temperature was then increased to 1100℃, and carbon dioxide was introduced into the heating zone for constant temperature activation for 2 hours. After cooling to room temperature, a spherical activated carbon carrier, designated SAC-4, was obtained. Detailed synthesis parameters are listed in Table 1, and specific surface area, pore volume, pore distribution, and other properties are listed in Table 2.

[0076] Example 5: Preparation of spherical activated carbon carrier

[0077] 10g of spherical phenolic resin was placed in the heating zone of a high-temperature furnace, and nitrogen gas was introduced (100mL / min). The furnace was heated to 1200℃, and carbonization was carried out at a constant temperature for 1 hour. After cooling to room temperature, a spherical carrier precursor was obtained. This precursor was mixed evenly with 10mL of a solution containing 2g of potassium hydroxide, and then dried at 110℃ to remove excess solvent. The resulting solid was placed in the heating zone of a high-temperature furnace, and nitrogen gas was introduced (100mL / min). The furnace was heated to 600℃, and activation was carried out at a constant temperature for 1 hour. After cooling to room temperature, the solid was washed successively with dilute hydrochloric acid and deionized water until the filtrate was neutral. After drying at 110℃, a spherical activated carbon carrier, designated SAC-5, was obtained. Its detailed synthesis parameters are listed in Table 1, and its specific surface area, pore volume, pore distribution, and other properties are listed in Table 2.

[0078] Example 6: Preparation of spherical activated carbon carrier

[0079] The process is basically the same as in Example 5, except that the activation temperature is changed to 500°C and the activation time is adjusted to 8h. All other conditions are exactly the same as in Example 5. A spherical activated carbon carrier, denoted as SAC-6, is obtained. Its detailed synthesis parameters are listed in Table 1, and its specific surface area, pore volume, pore distribution and other properties are listed in Table 2.

[0080] Comparative Example 1: Preparation of Spherical Activated Carbon Support

[0081] The process is basically the same as in Example 4, except that the activation temperature is increased to 1250°C. All other conditions are exactly the same as in Example 4. A spherical activated carbon carrier, denoted as DSAC-1, is obtained. Its detailed synthesis parameters are listed in Table 1, and its specific surface area, pore volume, pore distribution and other properties are listed in Table 2.

[0082] Comparative Example 2: Preparation of Spherical Activated Carbon Support

[0083] The process is basically the same as in Example 4, except that the spherical resin is directly cooled to room temperature after high-temperature carbonization without high-temperature activation treatment. All other conditions are exactly the same as in Example 4, resulting in a spherical activated carbon carrier, denoted as DSAC-2. Its detailed synthesis parameters are listed in Table 1, and its specific surface area, pore volume, pore distribution and other properties are listed in Table 2.

[0084] Table 1 is a summary table of the conditions for the above embodiments.

[0085]

[0086] Table 2 summarizes the properties of the spherical activated carbon carriers obtained in the above embodiments.

[0087]

[0088] Based on the data in Tables 1 and 2, it can be seen that the specific surface area of ​​the spherical activated carbon is 500–2000 m². 2 / g, pore volume is 0.55~1.5mL / g, and the ratio of micropores, mesopores and macropores is (1~10):(0.1~5):1.

[0089] Example 7: Preparation of Catalyst

[0090] The spherical activated carbon support SAC-1 obtained in Example 1 was sieved to obtain spherical activated carbon with a particle size of 0.4–2.0 mm. 1 g of the sieved spherical activated carbon was weighed and immersed in 1.7 mL of an aqueous solution containing 0.013 g chloroplatinic acid, 0.024 g stannous chloride, and 0.01 g potassium chloride for 1 hour. It was then dried in a water bath at 60–70 °C for 30 minutes, dried in an oven at 120 °C for 4 hours, and calcined at 350 °C for 4 hours under nitrogen protection. The resulting catalyst composition was: platinum: 0.5%, tin: 1.5%, potassium: 0.5%, with the remaining 97.5% being the support, denoted as Cat-1. Figure 3 Here is a physical image of the prepared Cat-1 catalyst, from... Figure 3 As can be seen, the catalyst Cat-1 appears as smooth black spheres with a diameter of 0.7–1.6 mm.

[0091] Example 8: Preparation of Catalyst

[0092] The spherical activated carbon support SAC-1 obtained in Example 1 was sieved to obtain spherical activated carbon with a particle size of 0.4–2.0 mm. 1 g of the sieved spherical activated carbon was weighed and immersed in 1.7 mL of an aqueous solution containing 0.026 g of chloroplatinic acid, 0.024 g of stannous chloride, and 0.03 g of potassium chloride for 0.5 h. It was then dried in a water bath at 60–70 °C for 30 min, dried in an oven at 120 °C for 4 h, and calcined at 350 °C for 4 h under nitrogen protection. The resulting catalyst composition was: platinum: 1.0%, tin: 1.5%, potassium: 1.5%, with the remaining 96% being the support, denoted as Cat-2.

[0093] Example 9: Preparation of Catalyst

[0094] The spherical activated carbon support SAC-1 obtained in Example 1 was sieved to obtain spherical activated carbon with a particle size of 0.4–2.0 mm. 1 g of the sieved spherical activated carbon was weighed and immersed in 1.7 mL of an aqueous solution containing 0.0026 g of chloroplatinic acid, 0.0008 g of stannous chloride, and 0.003 g of potassium chloride for 0.5 h. It was then dried in a water bath at 60–70 °C for 30 min, dried in an oven at 120 °C for 4 h, and calcined at 350 °C for 4 h under nitrogen protection. The resulting catalyst composition was: platinum: 0.1%, tin: 0.05%, potassium: 0.15%, with the remaining 99.7% being the support, denoted as Cat-3.

[0095] Example 10: Preparation of Catalyst

[0096] The spherical activated carbon support SAC-1 obtained in Example 1 was sieved to obtain spherical activated carbon with a particle size of 0.4–2.0 mm. 1 g of the sieved spherical activated carbon was weighed and immersed in 1.7 mL of an aqueous solution containing 0.013 g of chloroplatinic acid, 0.024 g of stannous chloride, and 0.025 g of sodium chloride for 12 h. The mixture was then dried in a water bath at 60–70 °C for 30 min, dried in an oven at 120 °C for 4 h, and calcined at 350 °C for 4 h under nitrogen protection. The resulting catalyst composition was: platinum: 0.5%, tin: 1.5%, sodium: 1.0%, with the remaining 97% being the support, denoted as Cat-4.

[0097] Example 11: Preparation of Catalyst

[0098] The spherical activated carbon support SAC-1 obtained in Example 1 was sieved to obtain spherical activated carbon with a particle size of 0.4–2.0 mm. 1 g of the sieved spherical activated carbon was weighed and immersed in 1.7 mL of an aqueous solution containing 0.026 g of chloroplatinic acid, 0.024 g of stannous chloride, and 0.05 g of sodium chloride for 0.5 h. It was then dried in a water bath at 60–70 °C for 30 min, dried in an oven at 120 °C for 4 h, and calcined at 350 °C for 4 h under nitrogen protection. The resulting catalyst composition was: platinum: 1.0%, tin: 1.5%, sodium: 2.0%, with the remaining 95.5% being the support, denoted as Cat-5.

[0099] Examples 12-16: Preparation of Catalysts

[0100] The process is basically the same as in Example 7, except that the spherical activated carbon in Example 7 is replaced with the spherical activated carbon supports SAC-2 to SAC-6 obtained in Examples 2-6. The rest of the operation is completely consistent with that in Example 7, and the resulting catalysts are referred to as Cat-6 to Cat-10, respectively.

[0101] Examples 17-18: Preparation of Catalysts

[0102] The process was basically the same as in Example 7, except that the calcination temperature in Example 7 was adjusted to 200°C and 800°C respectively. All other operations were completely consistent with those in Example 7, and the resulting catalysts were designated as Cat-11 to Cat-12 respectively.

[0103] Comparative Examples 3-4: Catalyst Preparation

[0104] The process is basically the same as in Example 7, except that the spherical activated carbon in Example 7 is replaced with the spherical activated carbon supports DSAC-1 to DSAC-2 obtained in Comparative Examples 1-2. The rest of the operation is completely consistent with that in Example 7, and the resulting catalysts are denoted as DCat-1 to DCat-2, respectively.

[0105] Comparative Example 5: Preparation of Catalyst

[0106] To further investigate the propane dehydrogenation performance of the catalyst prepared on a spherical activated carbon support, a catalyst was prepared in Comparative Example 5 using conventional spherical alumina (particle size 1.0-1.6 mm) as the support. Catalyst preparation method: 1 g of spherical alumina support was weighed and immersed in 1.7 mL of an aqueous solution containing 0.013 g of chloroplatinic acid, 0.024 g of stannous chloride, and 0.01 g of potassium chloride for 0.5 h. The catalyst was then dried in a water bath at 60-70 °C for 30 min, dried in an oven at 120 °C for 4 h, and calcined at 350 °C for 4 h under nitrogen protection. The resulting catalyst composition was: platinum: 0.5%, tin: 1.5%, potassium: 0.5%, with the remaining 97.5% being the support, denoted as DCat-3.

[0107] Comparative Example 6:

[0108] To further investigate the propane dehydrogenation performance of the catalyst prepared on a spherical activated carbon support, a catalyst was prepared in Comparative Example 6 using conventional coconut shell carbon (10-30 mesh) as the support. Catalyst preparation method: 1 g of coconut shell carbon support was weighed and immersed in 1.7 mL of an aqueous solution containing 0.013 g of chloroplatinic acid, 0.024 g of stannous chloride, and 0.01 g of potassium chloride for 0.5 h. The catalyst was then dried in a water bath at 60–70 °C for 30 min, dried in an oven at 120 °C for 4 h, and calcined at 350 °C for 4 h under nitrogen protection. The resulting catalyst composition was: platinum: 0.5%, tin: 1.5%, potassium: 0.5%, with the remaining 97.5% being the support, denoted as DCat-4.

[0109] Comparative Example 7: Catalyst Preparation

[0110] The process was basically the same as in Example 7, except that the chloroplatinic acid in Example 7 was adjusted to 0.039 g. The rest of the operation was completely consistent with that in Example 7. The resulting catalyst composition was: platinum: 1.5%, tin: 1.5%, potassium: 0.5%, and the remaining 96.5% was a support, denoted as DCat-5.

[0111] Comparative Example 8: Catalyst Preparation

[0112] The process is basically the same as in Example 7, except that the amount of stannous chloride added in Example 7 is adjusted to 0g, that is, no stannous chloride is added. The rest of the operation is completely consistent with that in Example 7. The resulting catalyst composition is: platinum: 0.5%, potassium: 0.5%, and the remaining 99% is support, denoted as DCat-6.

[0113] Table 3 summarizes the catalyst parameters prepared in Examples 7-18.

[0114]

[0115]

[0116] Example 19: Performance evaluation of propane dehydrogenation catalyst

[0117] The propane dehydrogenation performance of the catalysts prepared in Examples 7-18 and Comparative Examples 3-8 was evaluated in a quartz tubular fixed-bed reactor. The catalyst loading was 0.15 g (0.3 mL). Under H2 conditions, the temperature was increased to 600 °C at a rate of 5 °C / min, and reduction was carried out for 2 hours. Propane was then introduced, and the evaluation period was 24 hours. The reaction conditions were: temperature 600 °C, pressure 0.01 MPa, WHSV = 6 h. -1The molar ratio of H2 to C3H8 was 0.5. The reaction products were analyzed online by gas chromatography using an Agilent 7890A. The chromatographic conditions were: injection temperature 180℃, column oven temperature 105℃, FID detector temperature 200℃, and HP-Al2O3 / KCl column. The results of the propane dehydrogenation reaction of the catalyst are listed in Table 4.

[0118] Table 4 summarizes the results of the catalyst for propane dehydrogenation.

[0119] Catalyst name Initial conversion rate % Initial propylene selectivity % 24h conversion rate % 24h propylene selectivity % Cat-1 41.2 97.1 38.7 98.5 Cat-2 42.6 98.1 39.3 98.6 Cat-3 39.6 96.0 37.1 96.9 Cat-4 40.9 98.3 38.5 98.8 Cat-5 43.0 97.7 38.8 98.1 Cat-6 41.7 96.3 38.2 97.6 Cat-7 41.1 96.6 38.0 97.7 Cat-8 41.8 96.3 36.9 96.9 Cat-9 42.0 97.2 38.1 98.3 Cat-10 40.2 96.1 37.3 96.4 Cat-11 40.0 96.0 37.1 96.2 Cat-12 39.6 96.1 36.9 96.5 DCat-1 38.1 94.2 34.4 94.8 DCat-2 37.3 93.8 33.2 94.1 DCat-3 40.6 90.6 30.1 91.0 DCat-4 36.9 92.5 32.8 92.6 DCat-5 43.9 93.2 36.1 92.7 DCat-6 44.1 84.5 31.8 83.9

[0120] As shown in Table 4, the catalyst prepared by this invention with spherical activated carbon as support has high catalytic activity, propylene selectivity and catalytic stability. The initial propane conversion rate can reach 43% and the propylene selectivity can reach 98.3%. After 24 hours of reaction, the propane conversion rate can reach 39.3% and the propylene selectivity can reach 98.8%.

[0121] Example 20: Performance evaluation of propane dehydrogenation catalyst

[0122] The long-life performance of the catalyst Cat-1 prepared in Example 7 for propane dehydrogenation was evaluated in a quartz tubular fixed-bed reactor. The catalyst was loaded with 0.15 g (0.3 mL) and heated to 600 °C at a rate of 5 °C / min under H2 conditions. Reduction was carried out for 2 hours, followed by propane introduction. The evaluation period was 160 hours. The reaction conditions were: temperature 600 °C, pressure 0.01 MPa, WHSV = 6 h. -1 The molar ratio of H2 to C3H8 was 0.5. The reaction products were analyzed online by gas chromatography using an Agilent 7890A. The chromatographic conditions were: injection temperature 180℃, column oven temperature 105℃, FID detector temperature 200℃, and HP-Al2O3 / KCl column. The reaction results over time are shown in the curve below. Figure 4 As shown.

[0123] from Figure 4 As can be seen, during the long-term average process of 160h, the propane conversion of catalyst Cat-1 only decreased from 41.2% to 36.0%, and the propylene selectivity remained between 98% and 99%, demonstrating excellent catalytic stability and high propylene selectivity.

[0124] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A propane dehydrogenation catalyst, characterized in that, The propane dehydrogenation catalyst includes a support and a Pt component, a Sn component, and an alkali metal component supported on the support. The carrier is spherical activated carbon; The spherical activated carbon consists of spherical particles with a diameter of 0.4~2.0 mm and a specific surface area of ​​500~2000 m². 2 / g, pore volume is 0.55~1.5 mL / g; The spherical activated carbon has micropores with a pore size of 0.5–1.5 nm, mesopores with a pore size of 4–10 nm, and macropores with a pore size of 50–200 nm; the ratio of micropores, mesopores, and macropores in the spherical activated carbon is 1–10:0.1–5:

1. The alkali metal component is selected from at least one of potassium, lithium, and cesium.

2. The propane dehydrogenation catalyst according to claim 1, characterized in that, Based on the total weight of the propane dehydrogenation catalyst, the content of the support is 94.1~99.7 wt.%, the content of the Pt component (calculated as Pt element) is 0.1~1.0 wt.%, the content of the Sn component (calculated as Sn element) is 0.05~5.0 wt.%, and the content of the alkali metal component (calculated as alkali metal element) is 0.15~2.0 wt.%.

3. The propane dehydrogenation catalyst according to claim 1, characterized in that, When the alkali metal component is potassium, its content, calculated as potassium metal element, is 0.15~1.5 wt.%.

4. The propane dehydrogenation catalyst according to claim 1, characterized in that, When the alkali metal component is sodium, its content, calculated as sodium metal element, is 1.0~2.0 wt.%.

5. The method for preparing the propane dehydrogenation catalyst according to any one of claims 1 to 4, characterized in that, The preparation method includes: The support was impregnated in a mixture containing Pt component precursor, Sn component precursor and alkali metal component precursor, dried and calcined to obtain the propane dehydrogenation catalyst.

6. The preparation method according to claim 5, characterized in that, The carrier is spherical activated carbon, and the preparation method of the spherical activated carbon includes: In an inactive atmosphere, spherical polymers are carbonized and then activated by contact with an activator to obtain spherical activated carbon.

7. The preparation method according to claim 6, characterized in that, The spherical polymer is selected from at least one of phenolic resin, polystyrene resin, and polypropylene resin.

8. The preparation method according to claim 6, characterized in that, The activator is selected from at least one of water, carbon dioxide, potassium hydroxide, potassium carbonate, and phosphoric acid.

9. The preparation method according to claim 6, characterized in that, The inactive atmosphere is selected from at least one of nitrogen, argon, and helium.

10. The preparation method according to claim 6, characterized in that, The carbonization temperature is 600~1200℃, and the carbonization time is 1~8h.

11. The preparation method according to claim 6, characterized in that, The activation temperature is 500~1100℃, and the activation time is 1~8h.

12. The preparation method according to claim 5, characterized in that, The Pt component precursor is selected from chloroplatinic acid and / or platinum acetylacetonate.

13. The preparation method according to claim 5, characterized in that, The Sn component precursor is selected from at least one of stannous chloride and stannous tetrachloride.

14. The preparation method according to claim 5, characterized in that, The alkali metal precursor is selected from at least one of potassium chloride, sodium chloride, lithium chloride, potassium nitrate, sodium nitrate, and cesium chloride.

15. The preparation method according to claim 5, characterized in that, The amounts of the support, Pt component precursor, Sn component precursor, and alkali metal component precursor are such that, based on the total weight of the prepared propane dehydrogenation catalyst, the content of the support is 94.1~99.7 wt.%, the content of the Pt component (based on Pt elemental content) is 0.1~1.0 wt.%, the content of the Sn component (based on Sn elemental content) is 0.05~5.0 wt.%, and the content of the alkali metal component (based on alkali metal elemental content) is 0.15~2.0 wt.%.

16. The preparation method according to claim 5, characterized in that, The soaking time is 0.5 to 12 hours.

17. The preparation method according to claim 5, characterized in that, The drying temperature is 60~130℃, and the drying time is 0.5~6h.

18. The preparation method according to claim 5, characterized in that, The calcination temperature is 200~800℃, and the calcination time is 1~8h.

19. A method for producing propylene by dehydrogenation of propane, characterized in that, The method includes: dehydrogenating propane in the presence of a propane dehydrogenation catalyst and hydrogen to prepare propylene; The propane dehydrogenation catalyst is selected from the propane dehydrogenation catalysts according to any one of claims 1 to 4.

20. The method for producing propylene from propane by dehydrogenation according to claim 19, characterized in that, The conditions for the dehydrogenation reaction include: a reaction temperature of 450–700 °C, a reaction pressure of 0–0.5 MPa, and a propane weight hourly space velocity of 1–20 h⁻¹. -1 The hydrogen-hydrogen molar ratio is 0.25:1 to 10:1.

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