A method for preparing S-modified Pt-based molecular sieve catalysts and their application in propane dehydrogenation.

Abstract

A method for preparing a S-modified Pt-based molecular sieve catalyst and its application in propane dehydrogenation are disclosed. The catalyst mainly consists of a molecular sieve support, a primary active metal Pt, secondary active metals Sn, Cu, Zn, Ga, etc., and a secondary active non-metal S. By changing the content of the secondary non-metallic active component S and the high-temperature modification temperature, S species are introduced into the catalyst. The catalyst is prepared using a combination of hydrothermal crystallization and high-temperature gas-phase methods to modulate the interaction force and surface electronic structure between Pt metal sub-nano clusters and the promoter, thereby firmly stabilizing the Pt metal within the pores of the molecular sieve. The prepared S-modified Pt-based molecular sieve catalyst exhibits excellent high-temperature activity, selectivity, and stability in the propane dehydrogenation reaction and shows promising prospects for industrial application.

Description

Technical Field

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

[0002] Propane dehydrogenation is one of the most prominent key technologies in modern chemical industry, underpinning a rich and complex chemical industry chain. This technology holds a position second only to ethylene in the industrial field, with broad application prospects. Major downstream products include polypropylene, acrylonitrile, and propylene oxide, which are widely used in all aspects of daily life, covering food packaging, clothing fibers, building materials, and transportation, playing a vital role.

[0003] The emergence of propane dehydrogenation technology is inextricably linked to the rapid development of the chemical industry. Over the past few decades, with continuous advancements in science and technology and increasing societal demands, the petrochemical industry has gradually become an engine driving the modern economy. Against this backdrop, the demand for energy and chemical products has increased rapidly, and propane dehydrogenation technology has emerged as a key driver of this demand. However, traditional propylene production methods, primarily derived from naphtha cracking and catalytic cracking processes, face the dual challenges of increasing market demand and growing environmental pressure. Against this backdrop, direct propane dehydrogenation technology has emerged, becoming a hotly debated new technology in the industry. By utilizing propane as a feedstock, this technology not only reduces costs and achieves high propylene yields but is also more environmentally friendly and sustainable than traditional methods. This lays the foundation for achieving green and efficient propylene production.

[0004] In industrial propane dehydrogenation, PtSn / Al2O3 is widely used as the mainstream catalyst, but it faces serious problems in practical applications. Firstly, under high-temperature conditions (>600℃), PtSn / Al2O3 catalysts suffer from low conversion rates and are prone to carbon deposition. At high temperatures, the migration of Pt particles on the Al2O3 surface can cause sintering, accelerating catalyst deactivation. Furthermore, the catalyst is prone to carbon deposition in high-temperature environments, which not only reduces reactivity but also affects catalyst lifespan. High-temperature regeneration processes are energy-intensive and emit large amounts of CO2, causing environmental harm. This not only affects the economics of the process but also fails to meet the urgent needs of environmental friendliness and sustainable development. Therefore, there is an urgent need to develop a highly efficient, stable, and long-term propane dehydrogenation catalyst for propylene production that can maintain long-term activity under high temperature and high pressure conditions, reduce carbon deposition and sintering rates, thereby reducing regeneration frequency and improving the overall economics and environmental friendliness of the process. Through catalyst structure design, 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.

[0005] Molecular sieves are highly regarded in the field of catalysis due to their excellent thermal stability and ordered pore structure. This unique material not only performs exceptionally well in propane dehydrogenation but also exhibits superior performance in catalytic reactions, providing strong support for improving reaction selectivity and catalytic efficiency. First, the high thermal stability of molecular sieves allows them to maintain structural integrity under high-temperature conditions. This property is crucial for catalytic reactions, especially those requiring high temperatures like propane dehydrogenation. High thermal stability ensures that the molecular sieve does not undergo structural damage in high-temperature environments, thus extending its stability and lifespan in the catalytic process. Second, the ordered pore structure of molecular sieves provides ideal active sites for the reaction. In catalytic reactions, active sites are key to the catalyst's effectiveness. Molecular sieves, through their ordered pore structure, provide precise positions for reactant molecules, contributing to improved catalytic efficiency. This orderliness also helps avoid unnecessary side reactions, thereby improving reaction selectivity. Particularly noteworthy is the outstanding performance of molecular sieves in propane dehydrogenation. Their efficient conversion of propane to propylene makes this catalyst an ideal support. Molecular sieves can not only maintain catalytic activity under high temperature conditions, but also effectively prevent carbon deposition and sintering, thereby reducing the regeneration frequency and improving the overall economic efficiency of the process.

[0006] In propane dehydrogenation catalysts, besides metallic promoters, non-metallic promoters also play a crucial role in improving catalytic performance and optimizing reaction conditions. The introduction of these non-metallic promoters not only improves catalyst stability but also effectively enhances the selectivity and activity of the propane dehydrogenation reaction. Non-metallic promoters play a key role in the stability of propane dehydrogenation catalysts. Under high temperature and high pressure conditions, catalysts are prone to structural damage and deactivation. By introducing appropriate non-metallic promoters, the thermal stability of the catalyst can be improved, extending its service life. Non-metallic promoters have a significant impact on the selectivity of the propane dehydrogenation reaction. Introducing appropriate non-metallic promoters into the catalyst can regulate the reaction pathway and improve the selectivity for the target product. Furthermore, non-metallic promoters also regulate the surface acid-base properties and active sites of the catalyst, thereby affecting the catalytic activity. Through careful selection and design of non-metallic promoters, the acid-base properties of the catalyst surface can be adjusted, reaction conditions optimized, and the catalytic activity of the propane dehydrogenation reaction improved. Some non-metallic promoters can also alter the electronic structure of the catalyst, further optimizing its catalytic performance. It is particularly noteworthy that, compared with metallic promoters, non-metallic promoters often exhibit better resistance to poisoning. Metallic promoters can be affected by poisoning substances such as sulfur and chlorine, leading to a decrease in catalyst activity. Non-metallic promoters, on the other hand, are relatively more stable and have stronger resistance to poisoning substances, thus improving the long-term stability of the catalyst. In summary, the introduction of non-metallic promoters into propane dehydrogenation catalysts is crucial for improving catalytic performance. By improving catalyst stability and regulating reaction selectivity and activity, non-metallic promoters provide strong support for the efficient conduction of propane dehydrogenation reactions.

[0007] CN202111465502.8 discloses a catalyst using γ-Al₂O₃ nanospheres as a support, where excess Sn is used to dilute the active component Pt to a single-atom dispersed state. During high-temperature H₂ reduction, the surrounding Sn atoms are reduced through hydrogen spillover from Pt atoms, ultimately forming a PtSn disordered alloy sub-nano catalyst. CN202311211428.6 reveals a propane dehydrogenation catalyst with a highly stable diatomic structure, using γ-Al₂O₃ as a support, with Pt and Sn as active components, dispersed in a diatomic form. CN202011094682.9 describes 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, forming a composite molecular sieve. Pt and Sn active components are then impregnated onto this composite molecular sieve in steps, ultimately forming a PtSn / molecular sieve catalyst. Although these catalysts show significant improvements in stability compared to industrial Pt / Al2O3 catalysts, they still suffer from low catalytic activity and carbon deposition during high-temperature (>600℃) catalytic reactions. Therefore, despite the significant progress these catalysts have made in terms of stability, most still require further enhancement of catalytic activity and stability at high temperatures to meet the performance requirements of industrial high-temperature propane dehydrogenation processes. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing S-modified Pt-based molecular sieve catalysts. Another purpose is to provide an application of the Pt-based molecular sieve catalyst prepared by the above method in propane dehydrogenation.

[0009] The present invention adopts the following technical solution:

[0010] A method for preparing a S-modified Pt-based molecular sieve catalyst, wherein the catalyst support is a molecular sieve, the main metal active component is Pt metal, the secondary metal active component is any one of Sn, Cu, Zn, and Ga, and the secondary non-metal active component is S. 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 S is 0.10–10.0 wt%.

[0011] Furthermore, the specific steps include:

[0012] 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 = 1:0.10–2.00; silicon source / water = 1:1–100.0; silicon source / Pt metal compound = 1:0.0001–0.01; silicon source / secondary active metal compound = 1:0.0001–0.01.

[0013] Step 2: Slowly add the above mixed solution into the polytetrafluoroethylene lining of the stainless steel crystallization kettle, and continue to stir thoroughly to obtain a homogeneous mixed solution.

[0014] 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 a Pt-based@molecular sieve catalyst.

[0015] Step four: Place the Pt-based@molecular sieve catalyst in a tube furnace, and introduce a certain amount of S-containing gaseous compound under high temperature. Introduce S into the Pt-based@molecular sieve catalyst through a high-temperature gas phase method to obtain the modified Pt-based molecular sieve catalyst. The silicon source is calculated based on the SiO2 content, and the molar ratio of the amount of secondary non-metallic active S compound is: silicon source / secondary non-metallic active S compound = 1: 0.001~0.2.

[0016] Furthermore, in step one, the silicon source is any one or a mixture of several of silica sol, silica, and tetraethyl orthosilicate.

[0017] Furthermore, in step one, the template agent is any one or a mixture of several of tetramethylammonium hydroxide, tetraethylammonium hydroxide, and tetrapropylammonium hydroxide.

[0018] Furthermore, in step three, the crystallization temperature is 100–180℃, the crystallization time is 10–200h, the drying temperature is 100–180℃, the drying time is 1–100h, and the reduction temperature is 100–900℃, the reduction time is 1–100h.

[0019] Furthermore, in step four, the high-temperature gas phase temperature is 100–900℃, and the high-temperature time is 1–100h.

[0020] Furthermore, the main active metal component Pt compound is any one or a mixture of several of Pt(NO3)2(NH3)4 and H2PtCl6·6H2O.

[0021] Furthermore, the secondary active metal component metal compound is any one or a mixture of several of SnCl2, CuCl2, ZnCl2 and GaCl2.

[0022] Furthermore, the non-metallic active S compound is any one or a mixture of several of H2S, SO2 and SO3.

[0023] Application of Pt-based molecular sieve catalysts prepared by any of the above methods in propane dehydrogenation.

[0024] Furthermore, the method for using the above-mentioned modified Pt-based molecular sieve catalyst for propane dehydrogenation to propylene must follow the following process conditions:

[0025] (1) The modified Pt-based molecular sieve catalyst is shaped into 20-40 mesh granular catalyst;

[0026] (2) Weigh a certain mass of S-modified Pt-based molecular sieve catalyst and mix it evenly with 2g of quartz sand (20-60 mesh). Then fill the fixed bed reactor with an inner diameter of 12mm quartz tube and keep the catalyst in the constant temperature range of the device's heating furnace.

[0027] (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℃ / min; a certain amount of pure propane reaction gas is passed through the catalyst bed to carry out the catalytic dehydrogenation reaction.

[0028] Furthermore, the mass of the loaded catalyst in step (2) is 0.02–2.00 g; the pure propane gas is industrial propane;

[0029] Furthermore, the H2 pretreatment temperature in step (3) is 100–800°C; the reduction time is 1–20 h.

[0030] Furthermore, the reaction temperature described in step (3) is 400–800 °C;

[0031] Furthermore, the propane flow rate in step (3) is 10–100 mL / min, and the propane mass hourly space velocity (WHSV) is 2–1000 h⁻¹. -1 .

[0032] 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 combines high-temperature hydrothermal and high-temperature gas-phase methods to prepare S-modified Pt-based molecular sieve catalysts. 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 high-temperature gas-phase method, under high-temperature reduction conditions, on the one hand, the electron affinity of S species can adjust the oxidation state of Pt atoms; this electronic regulation helps optimize the catalytic performance of Pt species. On the other hand, changing the crystal structure of Pt species in the catalyst can enhance the dispersion and interaction of Pt atoms on the support, helping to slow down the sintering process of Pt atoms, improve the dispersion of Pt species in the catalytic reaction, and thus enhance its catalytic performance. Furthermore, S species can improve the adsorption capacity of Pt species for propane, enabling it to interact more effectively with reactants, increasing the adsorption sites of Pt species with reactant molecules such as propane, and improving the reaction efficiency. This invention involves adding an appropriate amount of non-metallic sulfur compounds during the high-temperature gas-phase treatment of Pt-based molecular sieves. Through interaction with Pt species, the overall catalytic performance of the Pt-based molecular sieve catalyst is improved. When applied to propane dehydrogenation, it exhibits superior propane conversion, propylene selectivity, and high-temperature stability, all significantly exceeding those of currently reported Pt-based catalysts.

[0033] The S-modified 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 S-modified Pt-based molecular sieve catalyst is approximately 62.5%, and the propylene selectivity is approximately 98.5%. In contrast, the initial propane conversion of the unmodified Pt-based molecular sieve catalyst (Comparative Example 1) is only approximately 49.5%, and the propylene selectivity is only approximately 90.1%, rapidly decreasing to approximately 25% after only 5 hours of reaction. Experimental results show that adjusting the S 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 catalyst's stability. Therefore, the S-modified Pt-based molecular sieve catalyst prepared in this invention possesses high propane conversion, high propylene selectivity, and high-temperature stability, demonstrating good potential for industrial application. Attached Figure Description

[0034] Figure 1 XRD patterns of the catalysts in Comparative Examples 1 to 3 and Examples 1 to 9;

[0035] Figure 2 SEM images of the PtSnSx@S-1(600) catalysts prepared in Comparative Example 1 and Examples 1 to 3. Detailed Implementation

[0036] The present invention will be further described below through specific embodiments.

[0037] Unless otherwise specified, all reagents used in the following examples were purchased commercially and not processed. Tetraethyl orthosilicate (TEOS), tetrapropylammonium hydroxide (TPAOH), chloroplatinic acid (H₂PtCl₆), stannous chloride (SnCl₂), copper chloride (CuCl₂), zinc chloride (ZnCl₂), and hydrogen sulfide (H₂S) 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.

[0038] The catalyst in the embodiment was named PtMS. x @S-1(y), where Pt represents the main active metal component; M represents the secondary active metal component; x represents the S content in the molecular sieve catalyst; and y represents the temperature in the high-temperature gas-phase process. For example, a PtSn@molecular sieve catalyst with a 0.5 wt.% S content modified at 600 degrees Celsius is PtSnS 0.5 @S-1(600).

[0039] Comparative Example 1 (without added compound S)

[0040] The preparation method specifically includes the following steps:

[0041] Step 1: Weigh 8.4g TEOS and 8.2g TPAOH respectively and dissolve them in 4.4g deionized water. Stir in a water bath at 25℃ for 3.0h until completely dissolved to obtain a homogeneous solution.

[0042] Step 2: Weigh 24 mg H2PtCl6·6H2O and dissolve it in 2.0 g of deionized water. Stir the solution in a 30°C water bath for 1 h to form a homogeneous solution. Then slowly add 0.2 mL NH2CH2CH2NH2 and continue stirring for 3.0 h to obtain a homogeneous Pt-containing solution.

[0043] Step 3: Weigh 16.0 mg SnCl2 and dissolve it in 2.0 g of deionized water. Stir the solution in a 30 °C water bath for 2 h to obtain a homogeneous Sn-containing solution.

[0044] Step 4: Mix the solutions from Steps 1, 2 and 3 together and continue stirring for 3 hours to form a homogeneous mixed solution. Finally, pour the above mixed solution into the polytetrafluoroethylene lining of the stainless steel crystallization kettle.

[0045] Step 5: Place the stainless steel crystallization vessel in an oven and heat it from room temperature to 175°C, maintaining a static hydrothermal reaction for 4 days. After crystallization, cool, centrifuge, wash, and dry at 100°C for 12 hours to obtain the PtSn@S-1 catalyst powder precursor.

[0046] 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 3h for reduction, and finally obtain the PtSn@S-1 catalyst.

[0047] Comparative Example 2 (without added compound S)

[0048] Its preparation method specifically includes the following steps:

[0049] Step 1: Weigh 8.4g TEOS and 8.2g TPAOH respectively and dissolve them in 4.4g deionized water. Stir in a water bath at 25℃ for 3.0h until completely dissolved to obtain a homogeneous solution.

[0050] Step 2: Weigh 24 mg H2PtCl6·6H2O and dissolve it in 2.0 g of deionized water. Stir the solution in a 30°C water bath for 1 h to form a homogeneous solution. Then slowly add 0.2 mL NH2CH2CH2NH2 and continue stirring for 3.0 h to obtain a homogeneous Pt-containing solution.

[0051] Step 3: Weigh 15.6 mg CuCl2 and dissolve it in 2.0 g deionized water. Stir the solution in a 30°C water bath for 2 hours to obtain a homogeneous Sn-containing solution.

[0052] Step 4: Mix the solutions from Steps 1, 2 and 3 together and continue stirring for 3 hours to form a homogeneous mixed solution. Finally, pour the above mixed solution into the polytetrafluoroethylene lining of the stainless steel crystallization kettle.

[0053] Step 5: Place the stainless steel crystallization vessel in an oven and heat it from room temperature to 175°C, maintaining a static hydrothermal reaction for 4 days. After crystallization, cool, centrifuge, wash, and dry at 100°C for 12 hours to obtain the PtCu@S-1 catalyst powder precursor.

[0054] Step 6: Place the PtCu@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 3h to reduce it, and finally obtain the PtCu@S-1 catalyst.

[0055] Comparative Example 3 (without added compound S)

[0056] Its preparation method specifically includes the following steps:

[0057] Step 1: Weigh 8.4g TEOS and 8.2g TPAOH respectively and dissolve them in 4.4g deionized water. Stir in a water bath at 25℃ for 3.0h until completely dissolved to obtain a homogeneous solution.

[0058] Step 2: Weigh 24 mg H2PtCl6·6H2O and dissolve it in 2.0 g of deionized water. Stir the solution in a 30°C water bath for 1 h to form a homogeneous solution. Then slowly add 0.2 mL NH2CH2CH2NH2 and continue stirring for 3.0 h to obtain a homogeneous Pt-containing solution.

[0059] Step 3: Weigh 17 mg ZnCl2 and dissolve it in 2.0 g of deionized water. Stir the solution in a 30°C water bath for 2 hours to obtain a homogeneous Sn-containing solution.

[0060] Step 4: Mix the solutions from Steps 1, 2, and 3 together and continue stirring for 3 hours to form a homogeneous mixed solution. Finally, pour 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 175°C, maintaining a static hydrothermal reaction for 4 days to crystallize. After crystallization, cool, centrifuge, wash, and dry at 100°C for 12 hours to obtain the PtZn@S-1 catalyst powder precursor.

[0062] Step 6: Place the PtZn@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 3h to reduce it, and finally obtain the PtZn@S-1 catalyst.

[0063] Example 1

[0064] Its preparation method specifically includes the following steps:

[0065] Step 1: Weigh 8.4g TEOS and 8.2g TPAOH respectively and dissolve them in 4.4g deionized water. Stir in a water bath at 25℃ for 3.0h until completely dissolved to obtain a homogeneous solution.

[0066] Step 2: Weigh 24 mg H2PtCl6·6H2O and dissolve it in 2.0 g of deionized water. Stir the solution in a 30°C water bath for 1 h to form a homogeneous solution. Then slowly add 0.2 mL NH2CH2CH2NH2 and continue stirring for 3.0 h to obtain a homogeneous Pt-containing solution.

[0067] Step 3: Weigh 16.0 mg SnCl2 and dissolve it in 2.0 g of deionized water. Stir the solution in a 30 °C water bath for 2 h to obtain a homogeneous Sn-containing solution.

[0068] Step 4: Mix the solutions from Steps 1, 2 and 3 together and continue stirring for 3 hours to form a homogeneous mixed solution. Finally, pour the above mixed solution into the polytetrafluoroethylene lining of the stainless steel crystallization kettle.

[0069] Step 5: Place the stainless steel crystallization vessel in an oven and heat it from room temperature to 175°C, maintaining a static hydrothermal reaction for 4 days. After crystallization, cool, centrifuge, wash, and dry at 100°C for 12 hours to obtain the PtSn@S-1 catalyst powder precursor.

[0070] 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 3h to reduce it, and finally obtain the PtSn@S-1 catalyst.

[0071] Step 7: Place the PtSn@S-1 catalyst in a tube furnace under an H2S atmosphere, raise the temperature to 600℃ at a rate of 2℃ / min, and maintain the temperature for 3 hours for reduction, finally obtaining PtSnS 0.5 @S-1(600) catalyst.

[0072] Example 2

[0073] Its preparation method specifically includes the following steps:

[0074] Step 1: Weigh 8.4g TEOS and 8.2g TPAOH respectively and dissolve them in 4.4g deionized water. Stir in a water bath at 25℃ for 3.0h until completely dissolved to obtain a homogeneous solution.

[0075] Step 2: Weigh 24 mg H2PtCl6·6H2O and dissolve it in 2.0 g of deionized water. Stir the solution in a 30°C water bath for 1 h to form a homogeneous solution. Then slowly add 0.2 mL NH2CH2CH2NH2 and continue stirring for 3.0 h to obtain a homogeneous Pt-containing solution.

[0076] Step 3: Weigh 16.0 mg SnCl2 and dissolve it in 2.0 g of deionized water. Stir the solution in a 30 °C water bath for 2 h to obtain a homogeneous Sn-containing solution.

[0077] Step 4: Mix the solutions from steps (1), (2) and (3) together and continue stirring for 3 hours to form a uniform mixed solution. Finally, put the above mixed solution into the polytetrafluoroethylene lining of the stainless steel crystallization kettle.

[0078] Step 5: Place the stainless steel crystallization vessel in an oven and heat it from room temperature to 175°C, maintaining a static hydrothermal reaction for 4 days. After crystallization, cool, centrifuge, wash, and dry at 100°C for 12 hours to obtain the PtSn@S-1 catalyst powder precursor.

[0079] 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 3h to reduce it, and finally obtain the PtSn@S-1 catalyst.

[0080] Step 7: Place the PtSn@S-1 catalyst in a tube furnace under an H2S atmosphere, raise the temperature to 600℃ at a rate of 2℃ / min, and maintain the temperature for 6 hours for reduction, finally obtaining PtSnS 1.0 @S-1(600) catalyst.

[0081] Example 3

[0082] Its preparation method specifically includes the following steps:

[0083] Step 1: Weigh 8.4g TEOS and 8.2g TPAOH respectively and dissolve them in 4.4g deionized water. Stir in a water bath at 25℃ for 3.0h until completely dissolved to obtain a homogeneous solution.

[0084] Step 2: Weigh 24 mg H2PtCl6·6H2O and dissolve it in 2.0 g of deionized water. Stir the solution in a 30°C water bath for 1 h to form a homogeneous solution. Then slowly add 0.2 mL NH2CH2CH2NH2 and continue stirring for 3.0 h to obtain a homogeneous Pt-containing solution.

[0085] Step 3: Weigh 16.0 mg SnCl2 and dissolve it in 2.0 g of deionized water. Stir the solution in a 30 °C water bath for 2 h to obtain a homogeneous Sn-containing solution.

[0086] Step 4: Mix the solutions from Steps 1, 2 and 3 together and continue stirring for 3 hours to form a homogeneous mixed solution. Finally, pour the above mixed solution into the polytetrafluoroethylene lining of the stainless steel crystallization kettle.

[0087] Step 5: Place the stainless steel crystallization vessel in an oven and heat it from room temperature to 175°C, maintaining a static hydrothermal reaction for 4 days. After crystallization, cool, centrifuge, wash, and dry at 100°C for 12 hours to obtain the PtSn@S-1 catalyst powder precursor.

[0088] 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 3h for reduction, and finally obtain the PtSn@S-1 catalyst.

[0089] Step 7: Place the PtSn@S-1 catalyst in a tube furnace under an H2S atmosphere, raise the temperature to 600℃ at a rate of 2℃ / min, and maintain the temperature for 9 hours to reduce it, finally obtaining PtSnS. 1.5 @S-1(600) catalyst.

[0090] Example 4

[0091] Its preparation method specifically includes the following steps:

[0092] Step 1: Weigh 8.4g TEOS and 8.2g TPAOH respectively and dissolve them in 4.4g deionized water. Stir in a water bath at 25℃ for 3.0h until completely dissolved to obtain a homogeneous solution.

[0093] Step 2: Weigh 24 mg H2PtCl6·6H2O and dissolve it in 2.0 g of deionized water. Stir the solution in a 30°C water bath for 1 h to form a homogeneous solution. Then slowly add 0.2 mL NH2CH2CH2NH2 and continue stirring for 3.0 h to obtain a homogeneous Pt-containing solution.

[0094] Step 3: Weigh 15.6 mg CuCl2 and dissolve it in 2.0 g deionized water. Stir the solution in a 30°C water bath for 2 hours to obtain a homogeneous Sn-containing solution.

[0095] Step 4: Mix the solutions from Steps 1, 2 and 3 together and continue stirring for 3 hours to form a homogeneous mixed solution. Finally, pour the above mixed solution into the polytetrafluoroethylene lining of the stainless steel crystallization kettle.

[0096] Step 5: Place the stainless steel crystallization vessel in an oven and heat it from room temperature to 175°C, maintaining a static hydrothermal reaction for 4 days. After crystallization, cool, centrifuge, wash, and dry at 100°C for 12 hours to obtain the PtCu@S-1 catalyst powder precursor.

[0097] Step 6: Place the PtCu@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 3h to reduce it, and finally obtain the PtCu@S-1 catalyst.

[0098] Step 7: Place the PtCu@S-1 catalyst in a tube furnace under an H2S atmosphere, raise the temperature to 600℃ at a rate of 2℃ / min, and maintain the temperature for 3 hours to reduce it, finally obtaining PtCuS. 0.5 @S-1(600) catalyst.

[0099] Example 5

[0100] Its preparation method specifically includes the following steps:

[0101] Step 1: Weigh 8.4g TEOS and 8.2g TPAOH respectively and dissolve them in 4.4g deionized water. Stir in a water bath at 25℃ for 3.0h until completely dissolved to obtain a homogeneous solution.

[0102] Step 2: Weigh 24 mg H2PtCl6·6H2O and dissolve it in 2.0 g of deionized water. Stir the solution in a 30°C water bath for 1 h to form a homogeneous solution. Then slowly add 0.2 mL NH2CH2CH2NH2 and continue stirring for 3.0 h to obtain a homogeneous Pt-containing solution.

[0103] Step 3: Weigh 15.6 mg CuCl2 and dissolve it in 2.0 g deionized water. Stir the solution in a 30°C water bath for 2 hours to obtain a homogeneous Sn-containing solution.

[0104] Step 4: Mix the solutions from Steps 1, 2 and 3 together and continue stirring for 3 hours to form a homogeneous mixed solution. Finally, pour the above mixed solution into the polytetrafluoroethylene lining of the stainless steel crystallization kettle.

[0105] Step 5: Place the stainless steel crystallization vessel in an oven and heat it from room temperature to 175°C, maintaining a static hydrothermal reaction for 4 days. After crystallization, cool, centrifuge, wash, and dry at 100°C for 12 hours to obtain the PtCu@S-1 catalyst powder precursor.

[0106] Step 6: Place the PtCu@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 3h to reduce it, and finally obtain the PtCu@S-1 catalyst.

[0107] Step 7: Place the PtCu@S-1 catalyst in a tube furnace under an H2S atmosphere, raise the temperature to 600℃ at a rate of 2℃ / min, and maintain the temperature for 6 hours to reduce it, finally obtaining PtCuS. 1.0 @S-1(600) catalyst.

[0108] Example 6

[0109] Its preparation method specifically includes the following steps:

[0110] Step 1: Weigh 8.4g TEOS and 8.2g TPAOH respectively and dissolve them in 4.4g deionized water. Stir in a water bath at 25℃ for 3.0h until completely dissolved to obtain a homogeneous solution.

[0111] Step 2: Weigh 24 mg H2PtCl6·6H2O and dissolve it in 2.0 g of deionized water. Stir the solution in a 30°C water bath for 1 h to form a homogeneous solution. Then slowly add 0.2 mL NH2CH2CH2NH2 and continue stirring for 3.0 h to obtain a homogeneous Pt-containing solution.

[0112] Step 3: Weigh 15.6 mg CuCl2 and dissolve it in 2.0 g deionized water. Stir the solution in a 30°C water bath for 2 hours to obtain a homogeneous Sn-containing solution.

[0113] Step 4: Mix the solutions from Steps 1, 2 and 3 together and continue stirring for 3 hours to form a homogeneous mixed solution. Finally, pour the above mixed solution into the polytetrafluoroethylene lining of the stainless steel crystallization kettle.

[0114] Step 5: Place the stainless steel crystallization vessel in an oven and heat it from room temperature to 175°C, maintaining a static hydrothermal reaction for 4 days. After crystallization, cool, centrifuge, wash, and dry at 100°C for 12 hours to obtain the PtCu@S-1 catalyst powder precursor.

[0115] Step 6: Place the PtCu@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 3h to reduce it, and finally obtain the PtCu@S-1 catalyst.

[0116] Step 7: The PtCu@S-1 catalyst was placed in a tube furnace under an H2S atmosphere and heated to 600℃ at a rate of 2℃ / min and maintained for 9 hours to reduce it, finally obtaining PtCuS. 1.5 @S-1(600) catalyst.

[0117] Example 7

[0118] Its preparation method specifically includes the following steps:

[0119] Step 1: Weigh 8.4g TEOS and 8.2g TPAOH respectively and dissolve them in 4.4g deionized water. Stir in a water bath at 25℃ for 3.0h until completely dissolved to obtain a homogeneous solution.

[0120] Step 2: Weigh 24 mg H2PtCl6·6H2O and dissolve it in 2.0 g of deionized water. Stir the solution in a 30°C water bath for 1 h to form a homogeneous solution. Then slowly add 0.2 mL NH2CH2CH2NH2 and continue stirring for 3.0 h to obtain a homogeneous Pt-containing solution.

[0121] Step 3: Weigh 17 mg ZnCl2 and dissolve it in 2.0 g of deionized water. Stir the solution in a 30°C water bath for 2 hours to obtain a homogeneous Sn-containing solution.

[0122] Step 4: Mix the solutions from Steps 1, 2 and 3 together and continue stirring for 3 hours to form a homogeneous mixed solution. Finally, pour the above mixed solution into the polytetrafluoroethylene lining of the stainless steel crystallization kettle.

[0123] Step 5: Place the stainless steel crystallization vessel in an oven and heat it from room temperature to 175°C, maintaining a static hydrothermal reaction for 4 days to crystallize. After crystallization, cool, centrifuge, wash, and dry at 100°C for 12 hours to obtain the PtZn@S-1 catalyst powder precursor.

[0124] Step 6: Place the PtZn@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 3h to reduce it, and finally obtain the PtZn@S-1 catalyst.

[0125] Step 7: Place the PtZn@S-1 catalyst in a tube furnace under an H2S atmosphere, raise the temperature to 600℃ at a rate of 2℃ / min, and maintain the temperature for 3 hours for reduction, finally obtaining PtZnS. 0.5 @S-1(600) catalyst.

[0126] Example 8

[0127] Its preparation method specifically includes the following steps:

[0128] Step 1: Weigh 8.4g TEOS and 8.2g TPAOH respectively and dissolve them in 4.4g deionized water. Stir in a water bath at 25℃ for 3.0h until completely dissolved to obtain a homogeneous solution.

[0129] Step 2: Weigh 24 mg H2PtCl6·6H2O and dissolve it in 2.0 g of deionized water. Stir the solution in a 30°C water bath for 1 h to form a homogeneous solution. Then slowly add 0.2 mL NH2CH2CH2NH2 and continue stirring for 3.0 h to obtain a homogeneous Pt-containing solution.

[0130] Step 3: Weigh 17 mg ZnCl2 and dissolve it in 2.0 g of deionized water. Stir the solution in a 30°C water bath for 2 hours to obtain a homogeneous Sn-containing solution.

[0131] Step 4: Mix the solutions from Steps 1, 2 and 3 together and continue stirring for 3 hours to form a homogeneous mixed solution. Finally, pour the above mixed solution into the polytetrafluoroethylene lining of the stainless steel crystallization kettle.

[0132] Step 5: Place the stainless steel crystallization vessel in an oven and heat it from room temperature to 175°C, maintaining a static hydrothermal reaction for 4 days to crystallize. After crystallization, cool, centrifuge, wash, and dry at 100°C for 12 hours to obtain the PtZn@S-1 catalyst powder precursor.

[0133] Step 6: Place the PtZn@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 3h to reduce it, and finally obtain the PtZn@S-1 catalyst.

[0134] Step 7: Place the PtZn@S-1 catalyst in a tube furnace under an H2S atmosphere, raise the temperature to 600℃ at a rate of 2℃ / min, and maintain the temperature for 6 hours to reduce it, finally obtaining PtZnS. 1.0 @S-1(600) catalyst.

[0135] Example 9

[0136] Its preparation method specifically includes the following steps:

[0137] Step 1: Weigh 8.4g TEOS and 8.2g TPAOH respectively and dissolve them in 4.4g deionized water. Stir in a water bath at 25℃ for 3.0h until completely dissolved to obtain a homogeneous solution.

[0138] Step 2: Weigh 24 mg H2PtCl6·6H2O and dissolve it in 2.0 g of deionized water. Stir the solution in a 30°C water bath for 1 h to form a homogeneous solution. Then slowly add 0.2 mL NH2CH2CH2NH2 and continue stirring for 3.0 h to obtain a homogeneous Pt-containing solution.

[0139] Step 3: Weigh 17 mg ZnCl2 and dissolve it in 2.0 g of deionized water. Stir the solution in a 30°C water bath for 2 hours to obtain a homogeneous Sn-containing solution.

[0140] Step 4: Mix the solutions from Steps 1, 2 and 3 together and continue stirring for 3 hours to form a homogeneous mixed solution. Finally, pour the above mixed solution into the polytetrafluoroethylene lining of the stainless steel crystallization kettle.

[0141] Step 5: Place the stainless steel crystallization vessel in an oven and heat it from room temperature to 175°C, maintaining a static hydrothermal reaction for 4 days to crystallize. After crystallization, cool, centrifuge, wash, and dry at 100°C for 12 hours to obtain the PtZn@S-1 catalyst powder precursor.

[0142] Step 6: Place the PtZn@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 3h to reduce it, and finally obtain the PtZn@S-1 catalyst.

[0143] Step 7: The PtZn@S-1 catalyst was placed in a tube furnace under an H2S atmosphere and heated to 600℃ at a rate of 2℃ / min and maintained for 9 hours for reduction, finally yielding PtZnS. 1.5 @S-1(600) catalyst.

[0144] The catalysts prepared in the comparative and example examples were used for propane dehydrogenation to propylene, and the specific results are shown in Table 1.

[0145] Table 1 PtMS with different S doping contents x Comparison of catalytic performance of @S-1 catalyst

[0146]

[0147]

[0148] Note: Reaction temperature: 600℃; Reactants: 100% C3H8; Propane mass hourly space velocity (WHSV): 6.0 h⁻¹ -1 .

[0149] In summary, combining Table 1 and... 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 the PtMSx@S-1 catalysts with different P contents have a regular MFI configuration pure silicon molecular sieve structure, and no diffraction peaks of the main active component Pt, the secondary active component M, and the S species were found, indicating that the highly dispersed metal nanoclusters PtMSx@S-1 catalyst was successfully synthesized. Figure 2The SEM images of the catalysts in Comparative Example 1 and Examples 1 to 3 show that the modification with different amounts of S species in the high-temperature gas phase had no effect on the morphology of the catalysts, which were all 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 S species). Furthermore, these catalysts maintained excellent propane conversion and propylene selectivity under high-temperature conditions, with minimal catalyst deactivation. In addition, 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 content of modified S species, the catalytic performance still exhibited high propane conversion and propylene selectivity. Examples 1, 4, and 7 also show that by keeping the S content constant and changing the types of secondary metal active components, the catalytic performance still exhibited high stability and propylene selectivity. The above fully demonstrates that the non-metallic sulfur compounds, as secondary active components, play a crucial role under high-temperature reduction conditions. On one hand, they can adjust the oxidation state of Pt atoms, and this electronic regulation mechanism helps optimize the catalytic performance of Pt species. On the other hand, by changing the crystal structure of Pt species in the catalyst, the dispersion and interaction of Pt atoms on the support can be enhanced, thereby effectively slowing down the sintering process of Pt atoms, increasing the dispersion of Pt species in the catalytic reaction, and thus enhancing its catalytic performance. Simultaneously, the introduction of sulfur species also improves the adsorption capacity of Pt species for propane, enabling it to interact more effectively with reactants. This improvement plays a key role in increasing the adsorption sites of Pt species with reactant molecules such as propane, significantly improving the reaction efficiency. This invention introduces an appropriate amount of non-metallic sulfur compounds into the high-temperature gas-phase treatment process, comprehensively improving the performance of Pt-based molecular sieve catalysts through interaction with Pt species. In the propane dehydrogenation reaction, this catalyst exhibits superior propane conversion, propylene selectivity, and high-temperature stability, far exceeding previously reported Pt-based catalysts. Therefore, the S-modified Pt-based @molecular sieve catalyst exhibits excellent performance in terms of high propane conversion, high propylene selectivity, and high-temperature stability, possessing broad industrial application potential. Compared with similar PtM propane dehydrogenation catalysts, its catalytic performance surpasses that of currently reported catalysts. In conclusion, the S-modified PtMSx@S-1 catalyst demonstrates excellent propane conversion, propylene selectivity, and high-temperature stability in propane dehydrogenation.

[0150] 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 an S-modified Pt-based molecular sieve catalyst, characterized in that: The catalyst is supported by a molecular sieve, the main metal active component is Pt metal, the secondary metal active component is any one of Sn, Cu, Zn, and Ga, and the secondary non-metal active component is S. 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 S is 0.10–10.0 wt%.

2. The method for preparing an S-modified Pt-based molecular sieve catalyst according to claim 1, characterized in that: Specifically, the following steps are included: 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 = 1:0.10~2.00; silicon source / water = 1:1~100.0; silicon source / Pt metal compound = 1:0.0001~0.01; silicon source / secondary metal active component metal compound = 1:0.0001~0.

01. Step 2: Slowly add the above mixed solution into the polytetrafluoroethylene lining of the stainless steel crystallization kettle, and continue to stir thoroughly to obtain a homogeneous mixed solution. 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 a Pt-based@molecular sieve catalyst. Step four: Place the Pt-based@molecular sieve catalyst in a tube furnace, and under high temperature conditions, introduce a certain amount of S-containing gaseous compound. Introduce S into the Pt-based@molecular sieve catalyst through a high-temperature gas-phase method to obtain the S-modified Pt-based molecular sieve catalyst. The silicon source is calculated based on the SiO2 content, and the molar ratio of the secondary non-metallic active component S compound is: silicon source / secondary non-metallic active component S compound = 1: 0.001~0.

2.

3. The method for preparing an S-modified Pt-based molecular sieve catalyst according to claim 2, characterized in that: In step one, the silicon source is any one or a mixture of several of silica sol, silica, and tetraethyl orthosilicate.

4. The method for preparing an S-modified Pt-based molecular sieve catalyst according to claim 2, characterized in that: In step one, the template agent is any one or a mixture of several of tetramethylammonium hydroxide, tetraethylammonium hydroxide, and tetrapropylammonium hydroxide.

5. The method for preparing an S-modified Pt-based molecular sieve catalyst according to claim 2, characterized in that: In step three, the crystallization temperature is 100–180 ℃ and the crystallization time is 10–200 h; the drying temperature is 100–180 ℃ and the drying time is 1–100 h; the reduction temperature is 100–900 ℃ and the reduction time is 1–100 h.

6. The method for preparing an S-modified Pt-based molecular sieve catalyst according to claim 2, characterized in that: In step four, the high-temperature gas phase temperature is 100–900 °C, and the high-temperature time is 1–100 h.

7. The method for preparing an S-modified Pt-based molecular sieve catalyst according to claim 2, characterized in that: The Pt metal compound is any one or a mixture of several of Pt(NO3)2(NH3)4 and H2PtCl6·6H2O.

8. The method for preparing an S-modified Pt-based molecular sieve catalyst according to claim 2, characterized in that: The secondary metal active component metal compound is any one of SnCl2, CuCl2, ZnCl2, and GaCl2.

9. The method for preparing an S-modified Pt-based molecular sieve catalyst according to claim 2, characterized in that: The non-metallic active component S compound is any one or a mixture of several of H2S, SO2 and SO3.

10. The application of the S-modified Pt-based molecular sieve catalyst prepared by the preparation method according to any one of claims 1 to 9 in propane dehydrogenation.

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