A method for preparing a P-doped Pt-based molecular sieve catalyst for propane dehydrogenation and a method for propane dehydrogenation to propylene.

Abstract

A method for preparing a P-doped Pt-based molecular sieve catalyst for propane dehydrogenation and a method for propane dehydrogenation to propylene are disclosed. The catalyst mainly consists of a molecular sieve support, a main active metal Pt, secondary active metals Sn, Fe, Co, Ni, etc., and a secondary active non-metal P. The catalyst is prepared using a one-pot hydrothermal crystallization method. By adjusting the loading of the secondary non-metallic active component P, the surface and electronic structures of the Pt species are altered, improving the efficiency of the catalytic reaction. This effectively encapsulates Pt-based metal sub-nano clusters within the pores of the molecular sieve. It also helps improve the catalyst's adsorption capacity for propane and its desorption capacity for propylene, thereby increasing the catalyst's activity and reducing the carbon deposition rate. The prepared P-doped Pt-based molecular sieve catalyst exhibits excellent ultra-high temperature stability and anti-carbon deposition performance in the propane dehydrogenation reaction, and also possesses good regeneration performance.

Description

Technical Field

[0001] This invention belongs to the field of industrial catalyst preparation, specifically relating to a method for preparing a P-doped Pt-based molecular sieve catalyst suitable for propane dehydrogenation in a fixed-bed reactor, and a method for propane dehydrogenation to propylene. Background Technology

[0002] In contemporary chemical industry, propane dehydrogenation technology has garnered significant attention, second only to ethylene in its crucial role in the industrial sector. Behind this technology lies a rich chemical industry chain, with major downstream products including polypropylene, acrylonitrile, and propylene oxide. These products permeate all aspects of daily life, playing a vital role in fields ranging from food packaging, clothing fibers, and building materials to transportation. Currently, propylene production primarily originates from naphtha cracking and catalytic cracking processes, but these two traditional methods are facing numerous challenges in meeting market demand. With the continuous increase in propylene demand, the industry urgently needs to improve production efficiency and reduce costs, thus necessitating the search for new propylene production pathways. Direct propane dehydrogenation to propylene has attracted considerable attention, becoming a hotly debated emerging technology in the industry. The key advantages of this technology lie in its use of propane as a feedstock, which has lower costs, while simultaneously achieving high propylene yields, and the obvious advantage of dedicated propylene production. Compared to traditional production methods, direct propane dehydrogenation technology not only offers higher economic benefits but is also more environmentally friendly and sustainable. The innovation of this process lies in optimizing catalysts and reaction conditions, which not only reduces the temperature and pressure requirements of the reaction but also improves selectivity and reduces energy consumption. This lays the foundation for achieving green and efficient propylene production. Under the dual pressures of global energy and environmental concerns, the research and application of direct propane dehydrogenation technology will bring new development directions to the energy industry.

[0003] In industrial propane dehydrogenation processes, PtSn / Al2O3 is widely used as the mainstream catalyst. However, it still faces a series of serious problems in practical applications. Firstly, PtSn / Al2O3 catalysts suffer from low conversion rates and easy carbon deposition under high-temperature (>600 °C) reaction conditions. Migration of Pt particles on the Al2O3 surface at high temperatures leads to sintering, accelerating catalyst deactivation. The catalyst is also prone to carbon deposition in high-temperature environments, which not only reduces reactivity but also affects catalyst lifespan. High-temperature regeneration processes are not only energy-intensive but also emit large amounts of CO2, posing environmental hazards. This not only affects the economics of the process but also fails to meet the current urgent needs for environmental friendliness and sustainable development. Therefore, there is an urgent need to develop a highly efficient and stable propane dehydrogenation catalyst with a long operating cycle. It should be able to maintain long-term activity under high temperature and high pressure conditions, reduce the incidence of carbon deposition and sintering, thereby reducing the frequency of regeneration and improving the overall economics and environmental friendliness of the process. Through structural design of the catalyst, it is hoped that new breakthroughs can be achieved in the field of propane dehydrogenation, driving the industry towards a more sustainable and green direction.

[0004] Molecular sieves are renowned for their exceptional thermal stability and ordered pore structure, making them ideal supports for propane dehydrogenation. Their outstanding stability ensures structural integrity even at high temperatures, while the ordered pore structure provides ideal active sites for the reaction, facilitating the efficient conversion of propane to propylene. This makes molecular sieves highly valued in the field of catalysis, providing strong support for improving reaction selectivity and catalytic efficiency.

[0005] CN202111465502.8 discloses a catalyst using γ-Al₂O₃ nanospheres as a support. Excess Sn is used to dilute the active component Pt to a single-atom dispersed state. During high-temperature H₂ reduction, the hydrogen overflow of Pt atoms reduces the surrounding Sn atoms, ultimately forming a PtSn disordered alloy sub-nano catalyst. CN202311211428.6 discloses a highly stable diatomic catalyst for propane dehydrogenation and its preparation method. The catalyst support is calcined and pretreated γ-Al₂O₃, and the active components are Pt and Sn, which are dispersed in a diatomic form. CN202011094682.9 discloses a composite molecular sieve catalyst for propane dehydrogenation to olefins and its preparation method. This catalyst consists of an acid-treated SAPO-34 molecular sieve and an alkali-treated HZSM-5 molecular sieve to form a composite molecular sieve. Pt and Sn active components are then impregnated onto the composite molecular sieve in steps to obtain a PtSn / molecular sieve catalyst. CN110479353 A、 Angew. Chem. Int. Ed., 2020, 59, 19450-19459 J Catal.,2020, 385, 61-69 reported the in-situ synthesis of sub-nanometer PtZn clusters in pure silica MFI molecular sieves, and the synthesis of PtZn catalysts encapsulated in MFI molecular sieves. All the catalysts prepared were supported and composed of the main active metal Pt and the secondary active metal M. They were tested at high temperatures (>600°C). o C) Low catalytic activity and easy carbon deposition occur during the catalytic reaction. Furthermore, compared to industrial Pt / Al2O3 catalysts, the stability of these catalysts has been significantly improved, but the high-temperature catalytic performance of most catalysts still needs improvement and cannot yet meet the performance requirements of industrial high-temperature propane dehydrogenation processes. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing a P-doped Pt-based molecular sieve catalyst for propane dehydrogenation. Another purpose is to provide a method for propane dehydrogenation to propylene.

[0007] The present invention adopts the following technical solution:

[0008] A method for preparing a P-doped Pt-based molecular sieve catalyst for propane dehydrogenation, wherein the catalyst support is a molecular sieve, the main metal active component is Pt, the secondary metal active component is any one of Sn, Fe, Co, and Ni, and the secondary non-metal active component is P. Based on the total mass of the catalyst, the loading of the main metal active component Pt is 0.01–1.00 wt%, the loading of the secondary metal active component is 0.01–1.00 wt%, and the loading of the secondary non-metal active component P is 0.10–10.0 wt%.

[0009] Its preparation method specifically includes the following steps:

[0010] Step 1: Thoroughly mix and stir the silicon source, template agent, water, main active component Pt metal compound, and secondary active metal compound to obtain a homogeneous mixed solution. The silicon source is calculated based on the SiO2 content, and the molar ratios of the various raw materials in the mixed solution system are as follows: silicon source / template agent = 1:0.10~1.00; silicon source / water = 1:1~50.0; silicon source / Pt metal compound = 1:0.0001~0.001; silicon source / secondary active metal compound = 1:0.0001~0.001.

[0011] Step 2: Slowly add the above mixed solution into the polytetrafluoroethylene lining of the stainless steel crystallization kettle, then add a certain amount of secondary non-metallic active P compound, and continue to stir thoroughly to obtain a homogeneous mixed solution; wherein, the silicon source is calculated based on the SiO2 content, and the molar ratio of the amount of secondary non-metallic active P compound is: silicon source / secondary non-metallic active P compound = 1: 0.001~0.1;

[0012] Step 3: Place the stainless steel crystallization kettle in a high-temperature oven and statically crystallize for a certain period of time to obtain a crystallized solid product. After filtration, multiple washings, and drying, the product is finally reduced to obtain the P-doped Pt-based molecular sieve catalyst.

[0013] Furthermore, the silicon source is any one or a mixture of several of the following: silica, tetraethyl orthosilicate, and silica sol.

[0014] Furthermore, the template agent is any one or a mixture of several of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide.

[0015] Furthermore, the main active metal component Pt compound is any one or a mixture of several of PtCl2, PtCl4, and H2PtCl6·6H2O.

[0016] Furthermore, the secondary active metal component metal compound is any one or a mixture of several of SnCl2, FeCl2, CoCl2 and NiCl2.

[0017] Furthermore, the non-metallic active P compound is any one or a mixture of several of PCl3, PCl5 and H3PO4.

[0018] Furthermore, in step three, the crystallization temperature is 100–200 °C, the crystallization time is 10–100 h, the drying temperature is 100–200 °C, the drying time is 5–50 h, and the reduction temperature is 100–900 °C, the reduction time is 5–50 h.

[0019] A method for producing propylene by dehydrogenation of propane includes the following steps:

[0020] (1) The obtained P-doped Pt-based molecular sieve catalyst is shaped into 20-60 mesh granular catalyst;

[0021] (2) Weigh a certain mass of Pt-based molecular sieve catalyst and mix it evenly with 2 g of quartz sand (20-60 mesh), then fill the fixed bed reactor with an inner diameter of 12 mm quartz tube, and keep the catalyst in the constant temperature range of the device's heating furnace;

[0022] (3) The catalyst is first pretreated with H2 for a period of time, and then cooled to room temperature; then heated to the temperature of propane dehydrogenation to propylene at a heating rate of 2 °C / min; a certain amount of pure propane reaction gas is passed through the catalyst bed to carry out the catalytic dehydrogenation reaction.

[0023] Furthermore, in step (3), the H2 pretreatment temperature is 100–700 °C; the reduction time is 1–10 h; the reaction temperature is 500–800 °C; the propane flow rate is 10–100 mL / min; and the propane space velocity is WHSV = 2–2000 h. -1 .

[0024] Furthermore, in step (2), the mass of the loaded catalyst is 0.02 to 1.00 g; the pure propane gas is industrial propane.

[0025] As can be seen from the above description of the present invention, compared with the prior art, the beneficial effects of the present invention are as follows: The catalyst of the present invention is a P-doped Pt-based molecular sieve catalyst prepared by one-pot crystallization. The size effect of the molecular sieve itself improves the dispersion and utilization rate of the Pt active component, encapsulating smaller Pt nanoclusters within the molecular sieve. Secondly, based on the one-pot crystallization of the molecular sieve raw material and the active metal, there is an interaction between Pt species and P species, which changes the surface structure and electronic structure of the Pt catalyst, improving the catalyst's adsorption capacity for propane and desorption capacity for propylene. When applied to the propane dehydrogenation reaction, it exhibits excellent propane conversion, propylene selectivity, and high-temperature stability, all far exceeding those of currently reported Pt-based catalysts. Therefore, the P-doped Pt-based molecular sieve catalyst prepared by the present invention has high propane conversion, high propylene selectivity, and high-temperature stability, and has good prospects for industrial application.

[0026] The P-doped Pt-based molecular sieve catalyst described in this invention exhibits excellent propane conversion and propylene selectivity in high-temperature propane dehydrogenation reactions. Taking a propane dehydrogenation reaction temperature of 650 °C as an example, the initial propane conversion of the P-doped Pt-based molecular sieve catalyst is approximately 60%, and the propylene selectivity is approximately 99%; while the initial propane conversion of the undoped Pt-based molecular sieve catalyst (Comparative Example 1) is only about 50%, and the propylene selectivity is about 91%, and it rapidly decreases to about 20% after only 4 hours of reaction. Experimental results show that controlling the P content in the Pt-based molecular sieve catalyst can not only improve the propane conversion and propylene selectivity of the catalyst, but also significantly improve the stability of the catalyst. Attached Figure Description

[0027] Figure 1 XRD patterns of the catalysts in Comparative Examples 1 to 3 and Examples 1 to 9;

[0028] Figure 2 SEM images of the PtSnPx@S-1 catalysts prepared in Comparative Example 1 and Examples 1 to 3. Detailed Implementation

[0029] The present invention will be further described below through specific embodiments.

[0030] Unless otherwise specified, all reagents used in the following examples were purchased commercially and not processed. Tetraethyl orthosilicate (TEOS), tetrapropylammonium hydroxide (TPAOH), chloroplatinic acid hexahydrate (H₂PtCl₆·6H₂O), stannous chloride (SnCl₂), ferrous chloride (FeCl₂), phosphorus trichloride (PCl₃), and phosphorus pentachloride (PCl₅) were all purchased from Aladdin Reagent Co., Ltd., and the deionized water used in the experiments came from the laboratory's high-purity water system.

[0031] The catalyst in the embodiment was named PtMP. x @S-1, where Pt represents the main active metal component; M represents the secondary active metal component; and x represents the P content in the molecular sieve catalyst. For example, a PtSn@molecular sieve catalyst doped with 0.5 wt.% P is designated as PtSnP. 0.5 @S-1.

[0032] Comparative Example 1 (without added compound P)

[0033] Its preparation method specifically includes the following steps:

[0034] Step 1: Weigh 4.2 g TEOS and 4.1 g TPAOH respectively and dissolve them in 2.2 g deionized water. Stir in a water bath at 25 ℃ for 2.5 h until completely dissolved to obtain a homogeneous solution.

[0035] Step 2: Weigh 12 mg H2PtCl6·6H2O and dissolve it in 1.0 g of deionized water. Stir the solution in a 30 ℃ water bath for 1 h to form a homogeneous solution. Then slowly add 0.1 mL NH2CH2CH2NH2 and continue stirring for 2.5 h to obtain a homogeneous Pt-containing solution.

[0036] Step 3: Weigh 8.1 mg SnCl2 and dissolve it in 1.0 g of deionized water. Stir the solution in a 30 ℃ water bath for 1 h to obtain a homogeneous Sn-containing solution.

[0037] Step 4: Mix the solutions from Steps 1, 2 and 3 together and continue stirring for 2 hours to form a homogeneous mixed solution. Finally, pour the above mixed solution into the polytetrafluoroethylene lining of the stainless steel crystallization kettle.

[0038] Step 5: Place the stainless steel crystallization vessel in an oven and heat it from room temperature to 170 ℃, maintaining a static hydrothermal reaction for 4 days for crystallization. After crystallization, cool, centrifuge, wash, and dry at 100 ℃ for 12 h to obtain the PtSn@S-1 catalyst powder precursor.

[0039] Step 6: Place the PtSn@S-1 catalyst powder precursor in a tube furnace under a high-purity H2 atmosphere, raise the temperature to 600 ℃ at a rate of 2 ℃ / min and maintain it for 3 h to reduce it, and finally obtain the PtSn@S-1 catalyst.

[0040] Comparative Example 2 (without added compound P)

[0041] Its preparation method includes the following steps:

[0042] Step 1: Weigh 4.2 g TEOS and 4.1 g TPAOH respectively and dissolve them in 2.2 g deionized water. Stir in a water bath at 25 ℃ for 2.5 h until completely dissolved to obtain a homogeneous solution.

[0043] Step 2: Weigh 12 mg H2PtCl6·6H2O and dissolve it in 1.0 g of deionized water. Stir the solution in a 30 ℃ water bath for 1 h to form a homogeneous solution. Then slowly add 0.1 mL NH2CH2CH2NH2 and continue stirring for 2.5 h to obtain a homogeneous Pt-containing solution.

[0044] Step 3: Weigh 7.2 mg FeCl2 and dissolve it in 1.0 g of deionized water. Stir the solution in a 30 ℃ water bath for 1 h to obtain a homogeneous Fe-containing solution.

[0045] Step 4: Mix the solutions from Steps 1, 2 and 3 together and continue stirring for 2 hours to form a homogeneous mixed solution. Finally, pour the above mixed solution into the polytetrafluoroethylene lining of the stainless steel crystallization kettle.

[0046] Step 5: Place the stainless steel crystallization vessel in an oven and heat it from room temperature to 170 ℃, maintaining a static hydrothermal reaction for 4 days for crystallization. After crystallization, cool, centrifuge, wash, and dry at 100 ℃ for 12 h to obtain the PtFe@S-1 catalyst powder precursor.

[0047] Step 6: Place the PtFe@S-1 catalyst powder precursor in a tube furnace under a high-purity H2 atmosphere, raise the temperature to 600 ℃ at a rate of 2 ℃ / min and maintain it for 3 h to reduce it, and finally obtain the PtFe@S-1 catalyst.

[0048] Comparative Example 3 (without added compound P)

[0049] Its preparation method includes the following steps:

[0050] Step 1: Weigh 4.2 g TEOS and 4.1 g TPAOH respectively and dissolve them in 2.2 g deionized water. Stir in a water bath at 25 ℃ for 2.5 h until completely dissolved to obtain a homogeneous solution.

[0051] Step 2: Weigh 12 mg H2PtCl6·6H2O and dissolve it in 1.0 g of deionized water. Stir the solution in a 30 ℃ water bath for 1 h to form a homogeneous solution. Then slowly add 0.1 mL NH2CH2CH2NH2 and continue stirring for 2.5 h to obtain a homogeneous Pt-containing solution.

[0052] Step 3: Weigh 8.3 mg of CoCl2 and dissolve it in 1.0 g of deionized water. Stir the solution in a 30 ℃ water bath for 1 h to obtain a homogeneous Co-containing solution.

[0053] Step four: Mix the solutions from steps one, two and three to form a homogeneous mixed solution. Finally, fill the polytetrafluoroethylene lining of the stainless steel crystallization reactor with the mixed solution.

[0054] Step 5: Place the stainless steel crystallization vessel in an oven and heat it from room temperature to 170 ℃, maintaining a static hydrothermal reaction for 4 days for crystallization. After crystallization, cool, centrifuge, wash, and dry at 100 ℃ for 12 h to obtain the PtCo@S-1 catalyst powder precursor.

[0055] Step 6: Place the PtCo@S-1 catalyst powder precursor in a tube furnace under a high-purity H2 atmosphere, raise the temperature to 600 ℃ at a rate of 2 ℃ / min and maintain it for 3 h to reduce it, and finally obtain the PtCo@S-1 catalyst. Example 1

[0056] Its preparation method includes the following steps:

[0057] Step 1: Weigh 4.2 g TEOS and 4.1 g TPAOH respectively and dissolve them in 2.2 g deionized water. Stir in a water bath at 25 ℃ for 2.5 h until completely dissolved to obtain a homogeneous solution.

[0058] Step 2: Weigh 12 mg H2PtCl6·6H2O and dissolve it in 1.0 g of deionized water. Stir the solution in a 30 ℃ water bath for 1 h to form a homogeneous solution. Then slowly add 0.1 mL NH2CH2CH2NH2 and continue stirring for 2.5 h to obtain a homogeneous Pt-containing solution.

[0059] Step 3: Weigh 8.1 mg SnCl2 and dissolve it in 1.0 g of deionized water. Stir the solution in a 30 ℃ water bath for 1 h to obtain a homogeneous Sn-containing solution.

[0060] Step 4: Mix the solutions from steps (1), (2) and (3), and add 0.28 g of PCl3 and continue stirring for 2 h to form a uniform mixed solution. Finally, put the above mixed solution into the polytetrafluoroethylene lining of the stainless steel crystallization kettle.

[0061] Step 5: Place the stainless steel crystallization vessel in an oven and heat it from room temperature to 170 °C, maintaining a static hydrothermal reaction for 4 days. After crystallization, cool, centrifuge, wash, and dry at 100 °C for 12 h to obtain PtSnP. 0.5 @S-1 catalyst powder precursor.

[0062] Step 6, PtSnP 0.5 The S-1 catalyst powder precursor was placed in a tube furnace under a high-purity H2 atmosphere and reduced to 600 °C at a heating rate of 2 °C / min for 3 h, ultimately yielding PtSnP. 0.5 @S-1 catalyst. Example 2

[0063] Its preparation method includes the following steps:

[0064] Step 1: Weigh 4.2 g TEOS and 4.1 g TPAOH respectively and dissolve them in 2.2 g deionized water. Stir in a water bath at 25 ℃ for 2.5 h until completely dissolved to obtain a homogeneous solution.

[0065] Step 2: Weigh 12 mg H2PtCl6·6H2O and dissolve it in 1.0 g of deionized water. Stir the solution in a 30 ℃ water bath for 1 h to form a homogeneous solution. Then slowly add 0.1 mL NH2CH2CH2NH2 and continue stirring for 2.5 h to obtain a homogeneous Pt-containing solution.

[0066] Step 3: Weigh 8.1 mg SnCl2 and dissolve it in 1.0 g of deionized water. Stir the solution in a 30 ℃ water bath for 1 h to obtain a homogeneous Sn-containing solution.

[0067] Step 4: Mix the solutions from steps (1), (2) and (3), and add 0.56 g of PCl3 and continue stirring for 2 h to form a uniform mixed solution. Finally, put the above mixed solution into the polytetrafluoroethylene lining of the stainless steel crystallization kettle.

[0068] Step 5: Place the stainless steel crystallization vessel in an oven and heat it from room temperature to 170 °C, maintaining a static hydrothermal reaction for 4 days. After crystallization, cool, centrifuge, wash, and dry at 100 °C for 12 h to obtain PtSnP. 1.0 @S-1 catalyst powder precursor.

[0069] Step 6, PtSnP 1.0 The S-1 catalyst powder precursor was placed in a tube furnace under a high-purity H2 atmosphere and reduced to 600 °C at a heating rate of 2 °C / min for 3 h, ultimately yielding PtSnP. 1.0 @S-1 catalyst. Example 3

[0070] Its preparation method includes the following steps:

[0071] Step 1: Weigh 4.2 g TEOS and 4.1 g TPAOH respectively and dissolve them in 2.2 g deionized water. Stir in a water bath at 25 ℃ for 2.5 h until completely dissolved to obtain a homogeneous solution.

[0072] Step 2: Weigh 12 mg H2PtCl6·6H2O and dissolve it in 1.0 g of deionized water. Stir the solution in a 30 ℃ water bath for 1 h to form a homogeneous solution. Then slowly add 0.1 mL NH2CH2CH2NH2 and continue stirring for 2.5 h to obtain a homogeneous Pt-containing solution.

[0073] Step 3: Weigh 8.1 mg SnCl2 and dissolve it in 1.0 g of deionized water. Stir the solution in a 30 ℃ water bath for 1 h to obtain a homogeneous Sn-containing solution.

[0074] Step 4: Mix the solutions from Steps 1, 2 and 3, and add 1.12 g of PCl3. Continue stirring for 2 h to form a homogeneous mixed solution. Finally, put the above mixed solution into the polytetrafluoroethylene lining of the stainless steel crystallization kettle.

[0075] Step 5: Place the stainless steel crystallization vessel in an oven and heat it from room temperature to 170 °C, maintaining a static hydrothermal reaction for 4 days. After crystallization, cool, centrifuge, wash, and dry at 100 °C for 12 h to obtain PtSnP. 2.0 @S-1 catalyst powder precursor.

[0076] Step 6, PtSnP 2.0 The S-1 catalyst powder precursor was placed in a tube furnace under a high-purity H2 atmosphere and reduced to 600 °C at a heating rate of 2 °C / min for 3 h, ultimately yielding PtSnP. 2.0 @S-1 catalyst. Example 4

[0077] Step 1: Weigh 4.2 g TEOS and 4.1 g TPAOH respectively and dissolve them in 2.2 g deionized water. Stir in a water bath at 25 ℃ for 2.5 h until completely dissolved to obtain a homogeneous solution.

[0078] Step 2: Weigh 12 mg H2PtCl6·6H2O and dissolve it in 1.0 g of deionized water. Stir the solution in a 30 ℃ water bath for 1 h to form a homogeneous solution. Then slowly add 0.1 mL NH2CH2CH2NH2 and continue stirring for 2.5 h to obtain a homogeneous Pt-containing solution.

[0079] Step 3: Weigh 7.2 mg FeCl2 and dissolve it in 1.0 g of deionized water. Stir the solution in a 30 ℃ water bath for 1 h to obtain a homogeneous Fe-containing solution.

[0080] Step 4: Mix the solutions from Steps 1, 2 and 3, and add 0.28 g of PCl3. Continue stirring for 2 h to form a homogeneous mixed solution. Finally, put the above mixed solution into the polytetrafluoroethylene lining of the stainless steel crystallization kettle.

[0081] Step 5: Place the stainless steel crystallization vessel in an oven and heat it from room temperature to 170 °C, maintaining a static hydrothermal reaction for 4 days to crystallize. After crystallization, cool, centrifuge, wash, and dry at 100 °C for 12 h to obtain PtFeP. 0.5 @S-1 catalyst powder precursor.

[0082] Step 6, PtFeP 0.5 The S-1 catalyst powder precursor was placed in a tube furnace under a high-purity H2 atmosphere and reduced to 600 °C at a heating rate of 2 °C / min for 3 h, ultimately yielding PtFeP. 0.5 @S-1 catalyst. Example 5

[0083] Its preparation method includes the following steps:

[0084] Step 1: Weigh 4.2 g TEOS and 4.1 g TPAOH respectively and dissolve them in 2.2 g deionized water. Stir in a water bath at 25 ℃ for 2.5 h until completely dissolved to obtain a homogeneous solution.

[0085] Step 2: Weigh 12 mg H2PtCl6·6H2O and dissolve it in 1.0 g of deionized water. Stir the solution in a 30 ℃ water bath for 1 h to form a homogeneous solution. Then slowly add 0.1 mL NH2CH2CH2NH2 and continue stirring for 2.5 h to obtain a homogeneous Pt-containing solution.

[0086] Step 3: Weigh 7.2 mg FeCl2 and dissolve it in 1.0 g of deionized water. Stir the solution in a 30 ℃ water bath for 1 h to obtain a homogeneous Fe-containing solution.

[0087] Step 4: Mix the solutions from Steps 1, 2 and 3, and add 0.56 g of PCl3. Continue stirring for 2 h to form a homogeneous mixed solution. Finally, put the above mixed solution into the polytetrafluoroethylene lining of the stainless steel crystallization kettle.

[0088] Step 5: Place the stainless steel crystallization vessel in an oven and heat it from room temperature to 170 °C, maintaining a static hydrothermal reaction for 4 days to crystallize. After crystallization, cool, centrifuge, wash, and dry at 100 °C for 12 h to obtain PtFeP.1.0 @S-1 catalyst powder precursor.

[0089] Step 6, PtFeP 1.0 The S-1 catalyst powder precursor was placed in a tube furnace under a high-purity H2 atmosphere and reduced to 600 °C at a heating rate of 2 °C / min for 3 h, ultimately yielding PtFeP. 1.0 @S-1 catalyst. Example 6

[0090] Its preparation method includes the following steps:

[0091] Step 1: Weigh 4.2 g TEOS and 4.1 g TPAOH respectively and dissolve them in 2.2 g deionized water. Stir in a water bath at 25 ℃ for 2.5 h until completely dissolved to obtain a homogeneous solution.

[0092] Step 2: Weigh 12 mg H2PtCl6·6H2O and dissolve it in 1.0 g of deionized water. Stir the solution in a 30 ℃ water bath for 1 h to form a homogeneous solution. Then slowly add 0.1 mL NH2CH2CH2NH2 and continue stirring for 2.5 h to obtain a homogeneous Pt-containing solution.

[0093] Step 3: Weigh 7.2 mg FeCl2 and dissolve it in 1.0 g of deionized water. Stir the solution in a 30 ℃ water bath for 1 h to obtain a homogeneous Fe-containing solution.

[0094] Step 4: Mix the solutions from Steps 1, 2 and 3, and add 1.12 g of PCl3. Continue stirring for 2 h to form a homogeneous mixed solution. Finally, put the above mixed solution into the polytetrafluoroethylene lining of the stainless steel crystallization kettle.

[0095] Step 5: Place the stainless steel crystallization vessel in an oven and heat it from room temperature to 170 °C, maintaining a static hydrothermal reaction for 4 days to crystallize. After crystallization, cool, centrifuge, wash, and dry at 100 °C for 12 h to obtain PtFeP. 2.0 @S-1 catalyst powder precursor.

[0096] Step 6: The PtFe@S-1 catalyst powder precursor was placed in a tube furnace under a high-purity H2 atmosphere and heated to 600 °C at a rate of 2 °C / min, and maintained at that temperature for 3 h to reduce it, finally obtaining PtFeP 2.0 @S-1 catalyst. Example 7

[0097] Its preparation method includes the following steps:

[0098] Step 1: Weigh 4.2 g TEOS and 4.1 g TPAOH respectively and dissolve them in 2.2 g deionized water. Stir in a water bath at 25 ℃ for 2.5 h until completely dissolved to obtain a homogeneous solution.

[0099] Step 2: Weigh 12 mg H2PtCl6·6H2O and dissolve it in 1.0 g of deionized water. Stir the solution in a 30 ℃ water bath for 1 h to form a homogeneous solution. Then slowly add 0.1 mL NH2CH2CH2NH2 and continue stirring for 2.5 h to obtain a homogeneous Pt-containing solution.

[0100] Step 3: Weigh 8.3 mg of CoCl2 and dissolve it in 1.0 g of deionized water. Stir the solution in a 30 ℃ water bath for 1 h to obtain a homogeneous Co-containing solution.

[0101] Step 4: Mix the solutions from Steps 1, 2 and 3, and add 0.28 g of PCl3. Continue stirring for 2 h to form a homogeneous mixed solution. Finally, put the above mixed solution into the polytetrafluoroethylene lining of the stainless steel crystallization kettle.

[0102] Step 5: Place the stainless steel crystallization vessel in an oven and heat it from room temperature to 170 °C, maintaining a static hydrothermal reaction for 4 days to crystallize. After crystallization, cool, centrifuge, wash, and dry at 100 °C for 12 h to obtain PtCoP. 0.5 @S-1 catalyst powder precursor.

[0103] Step 6, PtCoP 0.5 The S-1 catalyst powder precursor was placed in a tube furnace under a high-purity H2 atmosphere and reduced to 600 °C at a heating rate of 2 °C / min for 3 h, ultimately yielding PtCoP. 0.5 @S-1 catalyst. Example 8

[0104] Its preparation method includes the following steps:

[0105] Step 1: Weigh 4.2 g TEOS and 4.1 g TPAOH respectively and dissolve them in 2.2 g deionized water. Stir in a water bath at 25 ℃ for 2.5 h until completely dissolved to obtain a homogeneous solution.

[0106] Step 2: Weigh 12 mg H2PtCl6·6H2O and dissolve it in 1.0 g of deionized water. Stir the solution in a 30 ℃ water bath for 1 h to form a homogeneous solution. Then slowly add 0.1 mL NH2CH2CH2NH2 and continue stirring for 2.5 h to obtain a homogeneous Pt-containing solution.

[0107] Step 3: Weigh 8.3 mg of CoCl2 and dissolve it in 1.0 g of deionized water. Stir the solution in a 30 ℃ water bath for 1 h to obtain a homogeneous Co-containing solution.

[0108] Step 4: Mix the solutions from Steps 1, 2 and 3, and add 0.56 g of PCl3. Continue stirring for 2 h to form a homogeneous mixed solution. Finally, put the above mixed solution into the polytetrafluoroethylene lining of the stainless steel crystallization kettle.

[0109] Step 5: Place the stainless steel crystallization vessel in an oven and heat it from room temperature to 170 °C, maintaining a static hydrothermal reaction for 4 days to crystallize. After crystallization, cool, centrifuge, wash, and dry at 100 °C for 12 h to obtain PtCoP. 1.0 @S-1 catalyst powder precursor.

[0110] Step 6, PtCoP 1.0 The S-1 catalyst powder precursor was placed in a tube furnace under a high-purity H2 atmosphere and reduced to 600 °C at a heating rate of 2 °C / min for 3 h, ultimately yielding PtCoP. 1.0 @S-1 catalyst. Example 9

[0111] Its preparation method includes the following steps:

[0112] Step 1: Weigh 4.2 g TEOS and 4.1 g TPAOH respectively and dissolve them in 2.2 g deionized water. Stir in a water bath at 25 ℃ for 2.5 h until completely dissolved to obtain a homogeneous solution.

[0113] Step 2: Weigh 12 mg H2PtCl6·6H2O and dissolve it in 1.0 g of deionized water. Stir the solution in a 30 ℃ water bath for 1 h to form a homogeneous solution. Then slowly add 0.1 mL NH2CH2CH2NH2 and continue stirring for 2.5 h to obtain a homogeneous Pt-containing solution.

[0114] Step 3: Weigh 8.3 mg of CoCl2 and dissolve it in 1.0 g of deionized water. Stir the solution in a 30 ℃ water bath for 1 h to obtain a homogeneous Co-containing solution.

[0115] Step 4: Mix the solutions from Steps 1, 2 and 3, and add 1.12 g of PCl3. Continue stirring for 2 h to form a homogeneous mixed solution. Finally, put the above mixed solution into the polytetrafluoroethylene lining of the stainless steel crystallization kettle.

[0116] Step 5: Place the stainless steel crystallization vessel in an oven and heat it from room temperature to 170 °C, maintaining a static hydrothermal reaction for 4 days to crystallize. After crystallization, cool, centrifuge, wash, and dry at 100 °C for 12 h to obtain PtCoP.2.0 @S-1 catalyst powder precursor.

[0117] Step 6, PtCoP 2.0 The S-1 catalyst powder precursor was placed in a tube furnace under a high-purity H2 atmosphere and reduced to 600 °C at a heating rate of 2 °C / min for 3 h, ultimately yielding PtCoP. 2.0 @S-1 catalyst.

[0118] The catalysts prepared in the comparative example and the example were subjected to propane dehydrogenation reaction, and the specific results are shown in Table 1.

[0119] Table 1 PtMP with different P doping contents x Comparison of catalytic performance of @S-1 catalyst

[0120]

[0121] Note: Reaction temperature: 600 ℃; Reactants: 100% C3H8; Propane mass hourly space velocity (WHSV): 5.0 h⁻¹ -1 .

[0122] Combined with Table 1, Figure 1 and Figure 2 It can be seen that, Figure 1 The XRD patterns of the catalysts in Comparative Examples 1 to 3 and Examples 1 to 9 show that PtMP with different P contents... x The @S-1 catalyst exhibits a well-defined MFI configuration of pure silica molecular sieve, and no diffraction peaks were found for the main active component Pt, the secondary active component M, or P species, indicating the successful synthesis of highly dispersed PtMP metal nanoclusters. x @S-1 catalyst. Figure 2The SEM images of the catalysts in Comparative Example 1 and Examples 1 to 3 show that doping with different amounts of P species had no effect on the morphology of the catalysts, all exhibiting small hexagonal crystallites. Table 1 shows the catalytic performance results, indicating that the catalysts in Examples 1-9 exhibit significantly improved stability compared to the catalysts in Comparative Examples 1-3 (without P species doping). Furthermore, these catalysts maintain excellent propane conversion and propylene selectivity under high-temperature conditions, with minimal catalyst deactivation. Additionally, Examples 1, 2, and 3 demonstrate that by keeping the contents of the main active component Pt and the secondary active component Sn constant and changing the P doping content, the catalytic performance still exhibits high propane conversion and propylene selectivity. Examples 1, 4, and 7 show that by keeping the P content constant and changing the types of secondary metal active components, the catalytic performance still exhibits high stability and propylene selectivity. The above fully demonstrates that the non-metallic P compound, as a secondary active component, alters the surface and electronic structures of Pt, thereby enhancing the catalyst's activity and improving the efficiency of the catalytic reaction. Furthermore, it contributes to improving the catalyst's adsorption capacity for propane and its desorption capacity for propylene, thus resulting in a catalyst with strong catalytic activity and selectivity. Compared to similar PtM propane dehydrogenation catalysts, this catalytic performance surpasses that of currently reported catalysts. In conclusion, P-doped PtMP... x The @S-1 catalyst exhibits excellent propane dehydrogenation propane conversion, propylene selectivity, and high-temperature stability.

[0123] The above description is merely a preferred embodiment of the present invention and should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made in accordance with the scope of the present invention and the contents of the specification should still fall within the scope of the present invention.

Claims

1. A method for preparing a P-doped Pt-based molecular sieve catalyst for propane dehydrogenation, characterized in that: The catalyst is supported by a molecular sieve, with Pt as the main metallic active component, any one of Sn, Fe, Co, or Ni as the secondary metallic active component, and P as the secondary non-metallic active component. Based on the total mass of the catalyst, the loading of the main metallic active component Pt is 0.01–1.00 wt%, the loading of the secondary metallic active component is 0.01–1.00 wt%, and the loading of the secondary non-metallic active component P is 0.10–10.0 wt%. Its preparation method specifically includes the following steps: Step 1: Thoroughly mix and stir the silicon source, template agent, water, Pt metal compound, and secondary metal active component metal compound to obtain a homogeneous mixed solution. The silicon source is calculated based on the SiO2 content, and the molar ratios of the various raw materials in the mixed solution system are as follows: silicon source / template agent = 1:0.10~1.00; silicon source / water = 1:1~50.0; silicon source / Pt metal compound = 1:0.0001~0.001; silicon source / secondary metal active component metal compound = 1:0.0001~0.

001. Step 2: Slowly add the above mixed solution into the polytetrafluoroethylene lining of the stainless steel crystallization kettle, then add a certain amount of the secondary non-metallic active component P compound, and continue to stir thoroughly to obtain a homogeneous mixed solution; wherein, the silicon source is calculated based on the SiO2 content, and the molar ratio of the secondary non-metallic active component P compound is: silicon source / secondary non-metallic active component P compound = 1: 0.001~0.1; Step 3: Place the stainless steel crystallization kettle in a high-temperature oven and statically crystallize for a certain period of time to obtain a crystallized solid product. After filtration, multiple washings, and drying, the product is finally reduced to obtain the P-doped Pt-based molecular sieve catalyst.

2. The method for preparing a P-doped Pt-based molecular sieve catalyst for propane dehydrogenation according to claim 1, characterized in that: The silicon source is any one or a mixture of several of the following: silica, tetraethyl orthosilicate, and silica sol.

3. The method for preparing a P-doped Pt-based molecular sieve catalyst for propane dehydrogenation according to claim 1, characterized in that: The template agent is any one or a mixture of several of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide.

4. The method for preparing a P-doped Pt-based molecular sieve catalyst for propane dehydrogenation according to claim 1, characterized in that: The Pt metal compound is any one or a mixture of several of PtCl2, PtCl4, and H2PtCl6·6H2O.

5. The method for preparing a P-doped Pt-based molecular sieve catalyst for propane dehydrogenation according to claim 1, characterized in that: The secondary metal active component metal compound is any one of SnCl2, FeCl2, CoCl2, and NiCl2.

6. The method for preparing a P-doped Pt-based molecular sieve catalyst for propane dehydrogenation according to claim 1, characterized in that: The non-metallic active component P compound is any one or a mixture of several of PCl3, PCl5 and H3PO4.

7. The method for preparing a P-doped Pt-based molecular sieve catalyst for propane dehydrogenation according to claim 1, characterized in that: In step three, the crystallization temperature is 100–200 ℃ and the crystallization time is 10–100 h; the drying temperature is 100–200 ℃ and the drying time is 5–50 h; the reduction temperature is 100–900 ℃ and the reduction time is 5–50 h.

8. A method for producing propylene by dehydrogenation of propane, characterized in that: Includes the following steps: (1) The P-doped Pt-based molecular sieve catalyst prepared by any one of claims 1 to 7 is shaped into 20-60 mesh granular catalyst; (2) Weigh a certain mass of the P-doped Pt-based molecular sieve catalyst formed in step (1) and mix it evenly with 2 g of 20-60 mesh quartz sand. Then fill the mixture into a fixed bed reactor with an inner diameter of 12 mm quartz tube and keep the catalyst in the constant temperature range of the device's heating furnace. (3) The catalyst is first pretreated with H2 for a period of time, and then cooled to room temperature; then heated to the temperature of propane dehydrogenation to propylene at a heating rate of 2 °C / min; a certain amount of pure propane reaction gas is passed through the catalyst bed to carry out the catalytic dehydrogenation reaction.

9. The method for producing propylene from propane by dehydrogenation according to claim 8, characterized in that: In step (3), the H2 pretreatment temperature is 100–700 °C; the reduction time is 1–10 h; the reaction temperature is 500–800 °C; and the WHSV of pure propane is 2–2000 h⁻¹. -1 .

10. A method for producing propylene from propane by dehydrogenation according to claim 8, characterized in that: In step (2), the mass of the loaded catalyst is 0.02 to 1.00 g.

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