Multi-heteroatom doped pure silicon molecular sieve supported Pt-based propane dehydrogenation catalyst and preparation method thereof

Abstract

The invention discloses a multi-element heteroatom-doped pure silicon molecular sieve supported Pt-based catalyst as well as a preparation method and application of the multi-element heteroatom-doped pure silicon molecular sieve supported Pt-based catalyst. The Pt-based propane dehydrogenation catalyst is prepared by the following steps: preparing a multi-element heteroatom doped pure silicon molecular sieve through in-situ hydrothermal treatment and acid pickling, and loading an active metal component Pt by using the multi-element heteroatom doped pure silicon molecular sieve as a carrier and adopting an impregnation method. By regulating and controlling the electron interaction between Pt and the multi-element heteroatom doped pure silicon molecular sieve carrier, the sintering of Pt is avoided, the deposition of carbon deposit is inhibited, and the inactivation of the catalyst is slowed down, so that the catalyst can show excellent propylene yield in a high-temperature propane dehydrogenation reaction, and the obvious inactivation phenomenon does not occur after the reaction lasts for 48 hours. The invention provides a strategy for efficiently stabilizing Pt metal, the sintering resistance and carbon deposition resistance of the Pt-based catalyst can be remarkably improved, reliable technical support is provided for optimizing the catalytic performance, and the method is expected to become a universal strategy for preparing a high-stability catalyst.

Description

Technical Field

[0001] The present invention belongs to the field of catalyst preparation, and particularly relates to a Pt-based catalyst supported on a multi-heteroatom-doped pure-silica molecular sieve, a preparation method thereof, and an application thereof in propane dehydrogenation to propylene. Background Art

[0002] As a chemical intermediate and industrial raw material, propylene is the basic raw material for the three major synthetic materials, plastics, rubbers, and chemical fibers, and is mainly used in the production of downstream derivatives of polypropylene and propylene oxide. In recent years, the domestic demand has been increasing continuously. At present, the sources of propylene mainly include catalytic cracking, steam cracking, coal-to-propylene, and propane dehydrogenation. Among them, coal-to-propylene has disadvantages such as complex reaction processes and high energy consumption, while catalytic cracking and steam cracking also have disadvantages such as complex separation processes and low propylene yields. In contrast, propane dehydrogenation technology can obtain significantly higher propylene yields and propylene selectivities under high-temperature and low-pressure conditions, and has obvious advantages in terms of cost, energy consumption, environmental protection, propylene yield, and selectivity.

[0003] There are mainly eight processes for propane dehydrogenation in the industry, and the catalysts used are also different. Among them, Cr-based catalysts represented by the Catofin process and Pt-based catalysts represented by the Oleflex process are the most widely used. Cr-based catalysts have poor stability, and at the same time, Cr elements cause great environmental pollution, which greatly limits their development. Pt-based catalysts have high catalytic activity and excellent propylene selectivity, and are environmentally friendly, so they have gradually become the mainstream catalysts for propane dehydrogenation. However, in the actual industrial production process, the reaction temperature is above 600 °C, which leads to the problem of poor stability of Pt-based catalysts generally, and the catalysts are rapidly deactivated during the reaction process. Therefore, in order to continue the reaction, the catalyst needs to be regenerated repeatedly, which greatly increases the production cost. At the same time, pure propane feeding cannot be achieved in industrial production, and raw material pretreatment is required before propane feeding, which seriously affects the economic benefits. In addition, a large amount of chlorine gas is used in the regeneration of Pt-based catalysts, which not only causes the equipment to age and be damaged faster, but also pollutes the environment, which is seriously inconsistent with the concepts of green chemistry and sustainable development. Therefore, there is an urgent need to develop a Pt-based propane dehydrogenation catalyst with high stability.

[0004] To prepare a Pt-based propane dehydrogenation catalyst with high stability, the selected catalyst support should have good thermal stability and a large specific surface area. The good stability of the support can prevent the collapse of the support framework at high temperatures; while the large specific surface area can make the Pt metal more evenly distributed, further improving the stability of the catalyst. Compared with the commonly used industrial Al2O3 support, zeolite has better thermal stability and a larger specific surface area. It can still maintain a complete crystal structure at 1000 °C and has a developed and regular pore structure, which greatly increases its specific surface area. At the same time, the special pore structure of zeolite can encapsulate heteroatoms in the zeolite pores. By using the anchoring effect of heteroatoms on the active component Pt, not only highly dispersed sub-nano Pt clusters can be obtained, but also the sintering and growth of Pt particles during high-temperature reactions can be effectively inhibited, improving the stability of the catalyst. However, there are still some problems with zeolite supports. For example, most zeolites contain Al elements, which will greatly increase the acidity of the support and lead to catalyst deactivation due to carbon deposition. Summary of the Invention

[0005] To solve the problem of poor high-temperature stability of existing Pt-based propane dehydrogenation catalysts under harsh high-temperature reaction conditions, the present invention provides a Pt-based catalyst supported on a pure-silica zeolite doped with multiple heteroatoms and a preparation method thereof. The catalyst is prepared by in-situ hydrothermal synthesis and pickling to obtain a pure-silica zeolite doped with multiple heteroatoms as the support, and then using the impregnation method to disperse the active metal Pt on it, thereby obtaining the catalyst. Compared with traditional catalyst supports, using a pure-silica zeolite doped with multiple heteroatoms as the support can not only improve the dispersion degree of the metal on the support, but also effectively hinder the migration of metal particles at high temperatures, making the catalyst have more stable catalytic activity.

[0006] To achieve the above object, the present invention adopts the following technical solutions: A Pt-based catalyst supported on a pure-silica zeolite doped with multiple heteroatoms, which uses a pure-silica zeolite doped with multiple heteroatoms as the support and Pt as the active metal component; wherein the heteroatoms are selected from any two or more of Ce, Co, Cu, Cr, Bi, Fe, Ni, Ga, V, Sc, Y, La, W, Sb, Pb, Sn, Nb, Mn, Mo, V, Ti, Zn, In, Zr, Ge.

[0007] Further, based on the total mass of the catalyst, the total doping amount of the heteroatoms is 0.01 - 1.00 wt%, and the loading amount of the active metal component Pt is 0.01 - 1.00 wt%.

[0008] The preparation of the multi-heteroatom doped pure silicon molecular sieve supported Pt-based catalyst is to first prepare the multi-heteroatom doped pure silicon molecular sieve by in-situ hydrothermal and acid washing, and then load the active metal component Pt on the multi-heteroatom doped pure silicon molecular sieve by impregnation method, thereby obtaining the catalyst; it includes the following steps: (1) Preparation of pure silicon molecular sieve doped with multiple heteroatoms: The silicon source, template, water and heteroatom compound are fully mixed and stirred to obtain a uniform mixed solution, and then the mixed solution is slowly added to the polytetrafluoroethylene lining of a stainless steel crystallization kettle, and the stainless steel crystallization kettle is placed in a high-temperature oven for static crystallization. The obtained crystallized product is centrifuged, dried, ground, secondary dried and calcined, and then dissolved in a low-concentration nitric acid solution, and then stirred at high temperature, washed with water, centrifuged, dried and calcined to obtain a pure silicon molecular sieve doped with multiple heteroatoms; (2) Preparation of supported Pt-based catalysts: The Pt compound is added with water to form a solution, which is then added to the prepared pure silicon molecular sieve doped with multiple heteroatoms for impregnation. The obtained product is dried, ground, calcined and reduced to obtain the catalyst.

[0009] Furthermore, the silicon source in step (1) is any one or more of white carbon black, ethyl orthosilicate, water glass, and silica sol.

[0010] Furthermore, the template agent in step (1) is any one or more of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetramethylammonium bromide, and tetrabutylammonium bromide.

[0011] Furthermore, the heteroatom compound in step (1) is any two or more oxides, chlorides and / or nitrates of Ce, Co, Cu, Cr, Bi, Fe, Ni, Ga, V, Sc, Y, La, W, Sb, Pb, Sn, Nb, Mn, Mo, V, Ti, Zn, In, Zr, and Ge, and specifically may be any two or more of CeO2, CuCl2, Co(NO3)2, CrCl3, FeCl2, NiCl2, VCl3, ScCl3, GeO2, YCl3, LaCl3, In(NO3)2, Ga(NO3)2, MnCl2, SnCl2, Zn(NO3)2, Bi(NO3)3, Pb(NO3)3, SbCl3, WCl6, MoCl5, NbCl5, TiCl3, and Zr(NO3)4.

[0012] Furthermore, the molar ratio of the silicon source (in terms of SiO2), template, water and the total amount of heteroatoms used in step (1) is 1:(0.10-1.00):(1-50):(0.0001-0.001).

[0013] Further, the temperature of the static crystallization in step (1) is 80 - 180 °C, and the time is 8 - 80 h.

[0014] Further, the temperature of the drying in step (1) is 80 - 180 °C, and the time is 8 - 18 h.

[0015] Further, the temperature of the calcination in step (1) is 180 - 800 °C, and the time is 8 - 18 h.

[0016] Further, the concentration of the nitric acid solution in step (1) is 0.5 - 2.0 mol / L.

[0017] Further, the temperature of the high - temperature stirring in step (1) is 80 - 180 °C, and the time is 8 - 18 h.

[0018] Further, the Pt compound in step (2) is any one or several of PtCl2, PtCl4, H2PtCl6·6H2O, Pt(NH3)4(OH)2, and Pt(NH3)4Cl2·H2O.

[0019] Further, the treatment time of the impregnation in step (2) is 2 - 10 h.

[0020] Further, the temperature of the drying in step (2) is 80 - 180 °C, and the time is 8 - 18 h.

[0021] Further, the temperature of the calcination in step (2) is 180 - 800 °C, and the time is 8 - 18 h.

[0022] Further, the reduction in step (2) is carried out in a hydrogen atmosphere at 180 - 800 °C for 8 - 18 h.

[0023] The obtained multi - heteroatom - doped pure - silica molecular sieve - supported Pt - based catalyst can be used in the reaction of direct dehydrogenation of propane to propylene.

[0024] Further, the specific operation is as follows: First, the catalyst is formed into granular catalyst with 20 - 60 meshes, and then it is filled in a fixed - bed reactor equipped with a quartz tube with an inner diameter of 12 mm, and the catalyst is maintained in the constant - temperature zone of the heating furnace of the fixed - bed reactor; then, the catalyst is first pretreated with H2 (treated at 100 - 800 °C for 2 - 8 h), then raised to the reaction temperature (100 - 800 °C), and pure propane gas (WHSV = 4 - 2000 h -1 ) is introduced for catalytic dehydrogenation reaction.

[0025] The present invention first prepares a multi - heteroatom - doped pure - silica molecular sieve by an in - situ hydrothermal method, and removes large - particle metal oxides on the surface of the pure - silica molecular sieve by pickling. Then, using it as a carrier, the active metal Pt is loaded onto the surface of the carrier by an impregnation method to obtain the catalyst. Compared with single - heteroatom doping, the multi - heteroatom - doped pure - silica molecular sieve of the present invention can not only greatly reduce the surface carbon deposition of the catalyst, but also enhance the geometric effect, electronic effect and microstructure characteristics between the carrier and the Pt metal, and can more effectively provide multi - scale protection against different deactivation paths (sintering, poisoning, migration, etc.) of Pt under harsh conditions, so as to achieve strong stability in the reaction environment of pure propane feed, and further reduce the cost of industrial propane pretreatment.

[0026] The beneficial effects of the present invention are as follows: The present invention provides a multi - heteroatom - doped pure - silica molecular sieve - supported Pt - based catalyst with high stability and its preparation method. It uses an in - situ hydrothermally synthesized multi - heteroatom - doped pure - silica molecular sieve as a carrier. After pickling it, the active metal Pt is introduced into the carrier by an impregnation method. Compared with the molecular sieve carrier prepared by single - heteroatom doping, the pure - silica molecular sieve carrier prepared by multi - heteroatom doping of the present invention has good thermal stability and a large specific surface area, can improve the dispersion degree of the Pt active component, and can encapsulate Pt nanoclusters in the molecular sieve pores to limit the migration of the active component. At the same time, multi - heteroatom doping enables the active metal to be more uniformly dispersed on the surface of the catalyst carrier, and by using the anchoring effect of heteroatoms on the active component, the interaction force between the active component and the carrier can be improved to limit the migration and aggregation of Pt particles at high temperatures. Therefore, the use of the multi - heteroatom - doped pure - silica molecular sieve carrier is beneficial to maintaining the uniform distribution of Pt metal, improving the stability of the catalyst, so that it shows excellent high - temperature stability in the propane dehydrogenation reaction, and this preparation method has broad application prospects in the field of industrial catalysis. Brief Description of the Drawings

[0027] Figure 1 X - ray diffraction patterns (XRD) of the catalysts prepared in Examples 1 - 8.

[0028] Figure 2 Scanning electron micrographs (SEM) of the catalysts prepared in Examples 1 - 8.

[0029] Figure 3 High - angle annular dark - field scanning transmission electron micrograph (HADDF - STEM) of the PtSnIn@S - 1 catalyst prepared in Example 3. Detailed Description of the Invention

[0030] A multi-heteroatom doped pure silicon molecular sieve supported Pt-based catalyst, which uses a multi-heteroatom doped pure silicon molecular sieve as a carrier and Pt as an active metal component; wherein the heteroatoms are selected from any two or more of Ce, Co, Cu, Cr, Bi, Fe, Ni, Ga, V, Sc, Y, La, W, Sb, Pb, Sn, Nb, Mn, Mo, V, Ti, Zn, In, Zr, and Ge.

[0031] Based on the total mass of the catalyst, the total doping amount of heteroatoms is 0.01~1.00 wt%, and the loading amount of the active metal component Pt is 0.01~1.00 wt%.

[0032] The preparation of the polynary heteroatom-doped pure silicon molecular sieve supported Pt-based catalyst comprises the following steps: (1) Preparation of pure silicon molecular sieve doped with multiple heteroatoms: silicon source, template, water and heteroatom compound are mixed and stirred at a molar ratio of silicon source (in terms of SiO2), template, water and total heteroatom amount of 1:(0.10-1.00):(1-50):(0.0001-0.001) to obtain a uniform mixed solution, and then the mixed solution is slowly added to the polytetrafluoroethylene lining of a stainless steel crystallization kettle, and the stainless steel crystallization kettle is placed in a high-temperature oven and statically crystallized at 80-180 °C for 8-80 h. The obtained crystallized product is centrifuged, dried at 80-180 °C for 8-18 h, ground, dried at 80-180 °C for 8-18 h, and calcined at 180-800 °C for 8-18 h. The obtained product is then dissolved in 0.5-2.0 mol / L nitric acid solution and then subjected to 80-180 After stirring at high temperature for 8-18 hours, the mixture was washed with water and centrifuged, and finally dried at 80-180°C for 8-18 hours and calcined at 180-800°C for 8-18 hours to obtain a pure silicon molecular sieve doped with multiple heteroatoms. (2) Preparation of supported Pt-based catalysts: Add water to a Pt compound to prepare a solution, then add the above-prepared pure silicon molecular sieve doped with multiple heteroatoms and impregnate for 2 to 10 hours. The obtained product is dried at 80 to 180 °C for 8 to 18 hours, ground, calcined at 180 to 800 °C for 8 to 18 hours, and then reduced at 180 to 800 °C in a hydrogen atmosphere for 8 to 18 hours to obtain the catalyst.

[0033] Among them, the silicon source described in step (1) is any one or more of fumed silica, tetraethyl orthosilicate, sodium silicate, and silica sol. The template agent is any one or more of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetramethylammonium bromide, and tetrabutylammonium bromide. The heteroatom compound is any two or more of CeO2, CuCl2, Co(NO3)2, CrCl3, FeCl2, NiCl2, VCl3, ScCl3, GeO2, YCl3, LaCl3, In(NO3)2, Ga(NO3)2, MnCl2, SnCl2, Zn(NO3)2, Bi(NO3)3, Pb(NO3)3, SbCl3, WCl6, MoCl5, NbCl5, TiCl3, and Zr(NO3)4.

[0034] To make the content of the present invention easier to understand, the technical solutions of the present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited thereto.

[0035] The drugs used in the following examples were purchased through commercial channels and not treated without special instructions. Among them, tetrapropylammonium hydroxide (TPAOH), chloroplatinic acid hexahydrate (H2PtCl6·6H2O), cerium oxide (CeO2), copper chloride (CuCl2), cobalt nitrate (Co(NO3)2), chromium chloride (CrCl3), ferrous chloride (FeCl2), nickel chloride (NiCl2), vanadium chloride (VCl3), scandium chloride (ScCl3), germanium oxide (GeO2), yttrium chloride (YCl3), lanthanum chloride (LaCl3), indium nitrate (In(NO3)2), gallium nitrate (Ga(NO3)2), manganese chloride (MnCl2), tin chloride (SnCl4), zinc nitrate (Zn(NO3)2), bismuth nitrate (Bi(NO3)3), lead nitrate (Pb(NO3)3), antimony chloride (SbCl3), tungsten chloride (WCl6), molybdenum chloride (MoCl5), niobium chloride (NbCl5), titanium chloride (TiCl3), and zirconium nitrate (Zr(NO3)4) were all purchased from Aladdin Reagent Co., Ltd., and the deionized water used in the experimental process came from the high-purity water machine system in the laboratory.

[0036] Comparative Example 1 (1) Weigh 0.57 g of NaOH and 0.13 g of Al(OH)3 and dissolve them in 22.5 g of deionized water respectively. After stirring for 2.5 h to completely dissolve them, a homogeneous solution is obtained; (2) Weigh 1.11 g of TPABr and 16.67 g of silica gel and mix them with the solution in step (1). After stirring for 2.5 h to completely dissolve them, a homogeneous solution is obtained; (3)Weigh 45 mg of Co(NO3)2 and dissolve it in 1.0 g of deionized water. After stirring for 1 h, a homogeneous Co-containing solution is obtained; (4)Weigh 42 mg of FeCl2 and dissolve it in 1.0 g of deionized water. After stirring for 1 h, a homogeneous Fe-containing solution is obtained; (5)Mix the solutions obtained in steps (2), (3), and (4), and continue stirring for 5 h to form a homogeneous mixed solution. Then, load the above mixed solution into the polytetrafluoroethylene inner lining of a stainless-steel crystallization kettle; (6)Place the stainless-steel crystallization kettle in an oven, heat it from room temperature to 180 °C, and maintain static hydrothermal reaction crystallization for 3 days. After the crystallization is completed, cool it, centrifuge it, dry it at 80 °C for 12 h, grind it, dry it at 120 °C for 12 h, and finally place it in a muffle furnace and dry it at 550 °C for 12 h to obtain FeCo@ZSM-5 molecular sieve powder; (7)Weigh 40 mg of H2PtCl6·6H2O and dissolve it in 1.0 g of deionized water. After stirring for 1 h, a homogeneous Pt-containing solution is obtained; (8)Drop the solution obtained in step (7) and 4 g of H2O into the FeCo@ZSM-5 molecular sieve powder obtained in step (6), stir evenly, let it stand for 4 h, then dry it at 120 °C for 12 h, grind it, and place it in a muffle furnace and dry it at 550 °C for 12 h to obtain the precursor of PtFeCo@ZSM-5 catalyst powder; (9)Place the obtained precursor of PtFeCo@ZSM-5 catalyst powder in a tubular furnace, and in a high-purity H2 atmosphere, heat it to 600 °C at a rate of 2 °C·min -1 and hold for 3 h to finally obtain the PtFeCo@ZSM-5 catalyst, where the Pt loading is 0.3 wt%, the Fe doping amount is 0.37 wt%, and the Co doping amount is 0.29 wt%.

[0037] Comparative Example 2 (1)Weigh 0.57 g of NaOH and 0.13 g of Al(OH)3 respectively and dissolve them in 22.5 g of deionized water. After stirring for 2.5 h until completely dissolved, a homogeneous solution is obtained; (2)Weigh 1.11 g of TPABr and 16.67 g of silica gel respectively and mix them with the solution in step (1). After stirring for 2.5 h until completely dissolved, a homogeneous solution is obtained; (3)Weigh 36 mg of In(NO3)2 and dissolve it in 1.0 g of deionized water. After stirring for 1 h, a homogeneous In-containing solution is obtained; (4) Weigh 54 mg of SnCl4 and dissolve it in 1.0 g of deionized water. After stirring for 1 h, a homogeneous Sn-containing solution is obtained; (5) Mix the solutions obtained in steps (2), (3), and (4), and continue stirring for 5 h to form a homogeneous mixed solution. Then, transfer the above mixed solution into the PTFE inner lining of a stainless-steel crystallization kettle; (6) Place the stainless-steel crystallization kettle in an oven, heat it from room temperature to 180 °C, and maintain static hydrothermal reaction crystallization for 3 days. After the crystallization is completed, cool it, centrifuge it, dry it at 80 °C for 12 h, grind it, dry it at 120 °C for 12 h, and finally place it in a muffle furnace and dry it at 550 °C for 12 h to obtain SnIn@ZSM-5 molecular sieve powder; (7) Weigh 40 mg of H2PtCl6·6H2O and dissolve it in 1.0 g of deionized water. After stirring for 1 h, a homogeneous Pt-containing solution is obtained; (8) Add the solution obtained in step (7) and 4 g of H2O dropwise to the SnIn@ZSM-5 molecular sieve powder obtained in step (6). After stirring evenly, let it stand for 4 h, then dry it at 120 °C for 12 h, grind it, place it in a muffle furnace, and dry it at 550 °C for 12 h to obtain the PtSnIn@ZSM-5 catalyst powder precursor; (9) Place the obtained PtSnIn@ZSM-5 catalyst powder precursor in a tubular furnace. In a high-purity H2 atmosphere, heat it to 600 °C at a rate of 2 °C·min -1 and hold for 3 h to finally obtain the PtSnIn@ZSM-5 catalyst, where the Pt loading is 0.3 wt%, the Sn doping amount is 0.49 wt%, and the In doping amount is 0.35 wt%.

[0038] Comparative Example 3 (1) Weigh 16.24 g of TPAOH and 16.48 g of TEOS respectively, dissolve them in 7.0 g of deionized water, and stir for 2.5 h until completely dissolved to obtain a homogeneous solution; (2) Weigh 45 mg of Co(NO3)2 and dissolve it in 1.0 g of deionized water. After stirring for 1 h, a homogeneous Co-containing solution is obtained; (3) Mix the solutions obtained in steps (1) and (2), and continue stirring for 5 h to form a homogeneous mixed solution. Then, transfer the above mixed solution into the PTFE inner lining of a stainless-steel crystallization kettle; (4) Place the stainless-steel crystallization kettle in an oven, heat it from room temperature to 170 °C, and maintain static hydrothermal reaction crystallization for 2 days. After the crystallization is completed, cool it, centrifuge it, dry it at 80 °C for 12 h, grind it, dry it at 120 °C for 12 h, and finally place it in a muffle furnace and dry it at 550 °C for 12 h to obtain Co@S-1 molecular sieve powder; (5) Dissolve the obtained Co@S-1 molecular sieve powder in a 1.0 mol / L nitric acid solution, stir it in a water bath at 80 °C for 12 h, then wash it and centrifuge it several times, dry it in an oven at 120 °C for 12 h, and calcine it in a muffle furnace at 600 °C for 12 h to obtain highly dispersed Co@S-1 molecular sieve powder; (6) Weigh 40 mg of H2PtCl6·6H2O and dissolve it in 1.0 g of deionized water. After stirring for 1 h, a homogeneous Pt-containing solution is obtained; (7) Add the solution obtained in step (6) and 4 g of H2O dropwise to the highly dispersed Co@S-1 molecular sieve powder obtained in step (5), stir evenly, let it stand for 4 h, then dry it at 120 °C for 12 h, grind it, place it in a muffle furnace, and dry it at 550 °C for 12 h to obtain the precursor of PtCo@S-1 catalyst powder; (9) Place the obtained precursor of PtCo@S-1 catalyst powder in a tubular furnace. In a high-purity H2 atmosphere, heat it to 600 °C at a rate of 2 °C·min -1 and maintain it for 3 h. Finally, obtain the PtCo@S-1 catalyst, where the loading amount of Pt is 0.3 wt%, and the doping amount of Co is 0.29 wt%.

[0039] Comparative Example 4 (1) Weigh 16.24 g of TPAOH and 16.48 g of TEOS and dissolve them in 7.0 g of deionized water. After stirring for 2.5 h to completely dissolve them, a homogeneous solution is obtained; (2) Weigh 36 mg of In(NO3)2 and dissolve it in 1.0 g of deionized water. After stirring for 1 h, a homogeneous In-containing solution is obtained; (3) Mix the solutions obtained in steps (1) and (2), and continue to stir for 5 h to form a homogeneous mixed solution. Then, load the above mixed solution into the polytetrafluoroethylene inner lining of a stainless-steel crystallization kettle; (4) Place the stainless-steel crystallization kettle in an oven, heat it from room temperature to 170 °C, and maintain static hydrothermal reaction crystallization for 2 days. After the crystallization is completed, cool it, centrifuge it, dry it at 80 °C for 12 h, grind it, dry it at 120 °C for 12 h, and finally place it in a muffle furnace and dry it at 550 °C for 12 h to obtain In@S-1 molecular sieve powder; (5) The obtained In@S-1 molecular sieve powder was dissolved in a 1.0 mol / L nitric acid solution, stirred in a water bath at 80 °C for 12 h, washed and centrifuged multiple times, dried in an oven at 120 °C for 12 h, and calcined in a muffle furnace at 600 °C for 12 h to obtain highly dispersed In@S-1 molecular sieve powder; (6) Weighed 40 mg of H2PtCl6·6H2O and dissolved it in 1.0 g of deionized water. After stirring for 1 h, a homogeneous Pt-containing solution was obtained; (7) The solution obtained in step (6) and 4 g of H2O were added dropwise to the highly dispersed In@S-1 molecular sieve powder obtained in step (5). After stirring evenly, it was left standing for 4 h, then dried at 120 °C for 12 h, and then ground. After that, it was placed in a muffle furnace and dried at 550 °C for 12 h to obtain the PtIn@S-1 catalyst powder precursor; (9) The obtained PtIn@S-1 catalyst powder precursor was placed in a tubular furnace. In a high-purity H2 atmosphere, it was heated to 600 °C at a rate of 2 °C·min -1 and maintained for 3 h. Finally, the PtIn@S-1 catalyst was obtained, where the Pt loading was 0.3 wt% and the In doping amount was 0.35 wt%.

[0040] Example 1 (1) Weighed 16.24 g of TPAOH and 16.48 g of TEOS and dissolved them in 7.0 g of deionized water. After stirring for 2.5 h to completely dissolve them, a homogeneous solution was obtained; (2) Weighed 23 mg of ScCl3 and dissolved it in 1.0 g of deionized water. After stirring for 1 h, a homogeneous Sc-containing solution was obtained; (3) Weighed 39 mg of CuCl2 and dissolved it in 1.0 g of deionized water. After stirring for 1 h, a homogeneous Cu-containing solution was obtained; (4) The solutions obtained in steps (1), (2), and (3) were mixed and stirred continuously for 5 h to form a uniform mixed solution. Then, the above mixed solution was filled into the polytetrafluoroethylene lining of a stainless-steel crystallization kettle; (5) The stainless-steel crystallization kettle was placed in an oven, heated from room temperature to 170 °C, and maintained for static hydrothermal reaction crystallization for 2 days. After the crystallization was completed, it was cooled, centrifuged, dried at 80 °C for 12 h, ground, dried at 120 °C for 12 h, and finally placed in a muffle furnace and dried at 550 °C for 12 h to obtain CuSc@S-1 molecular sieve powder; (6) Dissolve the obtained CuSc@S-1 molecular sieve powder in 1.0 mol / L nitric acid solution, stir in a water bath at 80 °C for 12 h, then wash and centrifuge it multiple times, dry it in an oven at 120 °C for 12 h, and calcine it in a muffle furnace at 600 °C for 12 h to obtain highly dispersed CuSc@S-1 molecular sieve powder; (7) Weigh 40 mg of H2PtCl6·6H2O and dissolve it in 1.0 g of deionized water. After stirring for 1 h, a homogeneous Pt-containing solution is obtained; (8) Add the solution obtained in step (7) and 4 g of H2O dropwise to the highly dispersed CuSc@S-1 molecular sieve powder obtained in step (6). After stirring evenly, let it stand for 4 h, then dry it at 120 °C for 12 h, and after grinding, place it in a muffle furnace and dry it at 550 °C for 12 h to obtain the precursor of PtCuSc@S-1 catalyst powder; (9) Place the obtained precursor of PtCuSc@S-1 catalyst powder in a tubular furnace. In a high-purity H2 atmosphere, heat it to 600 °C at a rate of 2 °C·min -1 and keep it for 3 h. Finally, obtain the PtCuSc@S-1 catalyst, where the loading amount of Pt is 0.3 wt%, the doping amount of Cu is 0.37 wt%, and the doping amount of Sc is 0.14 wt%.

[0041] Example 2 (1) Weigh 16.24 g of TPAOH and 16.48 g of TEOS respectively and dissolve them in 7.0 g of deionized water. After stirring for 2.5 h until completely dissolved, a homogeneous solution is obtained; (2) Weigh 45 mg of Co(NO3)2 and dissolve it in 1.0 g of deionized water. After stirring for 1 h, a homogeneous Co-containing solution is obtained; (3) Weigh 42 mg of FeCl2 and dissolve it in 1.0 g of deionized water. After stirring for 1 h, a homogeneous Fe-containing solution is obtained; (4) Mix the solutions obtained in steps (1), (2), and (3), and continue to stir for 5 h to form a homogeneous mixed solution. Then put the above mixed solution into the PTFE liner of a stainless-steel crystallization kettle; (5) Place the stainless-steel crystallization kettle in an oven, heat it from room temperature to 170 °C, and keep it for static hydrothermal reaction crystallization for 2 days. After the crystallization is completed, cool it, centrifuge it, dry it at 80 °C for 12 h, then grind it, dry it at 120 °C for 12 h, and finally place it in a muffle furnace and dry it at 550 °C for 12 h to obtain FeCo@S-1 molecular sieve powder; (6) Dissolve the obtained FeCo@S-1 molecular sieve powder in 1.0 mol / L nitric acid solution, stir in a water bath at 80 °C for 12 h, then wash and centrifuge multiple times, dry in an oven at 120 °C for 12 h, and calcine in a muffle furnace at 600 °C for 12 h to obtain highly dispersed FeCo@S-1 molecular sieve powder; (7) Weigh 40 mg of H2PtCl6·6H2O and dissolve it in 1.0 g of deionized water. After stirring for 1 h, a homogeneous Pt-containing solution is obtained; (8) Add the solution obtained in step (7) and 4 g of H2O dropwise to the highly dispersed FeCo@S-1 molecular sieve powder obtained in step (6). After stirring evenly, let it stand for 4 h, then dry at 120 °C for 12 h, and then grind it. Place it in a muffle furnace and dry at 550 °C for 12 h to obtain the PtFeCo@S-1 catalyst powder precursor; (9) Place the obtained PtFeCo@S-1 catalyst powder precursor in a tubular furnace. In a high-purity H2 atmosphere, heat it at a rate of 2 °C·min -1 to 600 °C and hold for 3 h. Finally, obtain the PtFeCo@S-1 catalyst, where the Pt loading is 0.3 wt%, the Fe doping amount is 0.37 wt%, and the Co doping amount is 0.29 wt%.

[0042] Example 3 (1) Weigh 16.24 g of TPAOH and 16.48 g of TEOS and dissolve them in 7.0 g of deionized water. After stirring for 2.5 h to completely dissolve them, a homogeneous solution is obtained; (2) Weigh 36 mg of In(NO3)2 and dissolve it in 1.0 g of deionized water. After stirring for 1 h, a homogeneous In-containing solution is obtained; (3) Weigh 54 mg of SnCl4 and dissolve it in 1.0 g of deionized water. After stirring for 1 h, a homogeneous Sn-containing solution is obtained; (4) Mix the solutions obtained in steps (1), (2), and (3), and continue to stir for 5 h to form a uniform mixed solution. Then, put the above mixed solution into the polytetrafluoroethylene liner of a stainless-steel crystallization kettle; (5) Place the stainless-steel crystallization kettle in an oven, heat it from room temperature to 170 °C, and maintain static hydrothermal reaction crystallization for 2 days. After the crystallization is completed, cool, centrifuge, dry at 80 °C for 12 h, then grind it, dry at 120 °C for 12 h, and finally place it in a muffle furnace and dry at 550 °C for 12 h to obtain SnIn@S-1 molecular sieve powder; (6) Dissolve the obtained SnIn@S-1 molecular sieve powder in 1.0 mol / L nitric acid solution, stir in a water bath at 80 °C for 12 h, then wash and centrifuge it multiple times, dry it in an oven at 120 °C for 12 h, and calcine it in a muffle furnace at 600 °C for 12 h to obtain highly dispersed SnIn@S-1 molecular sieve powder; (7) Weigh 40 mg of H2PtCl6·6H2O and dissolve it in 1.0 g of deionized water. After stirring for 1 h, a homogeneous Pt-containing solution is obtained; (8) Add the solution obtained in step (7) and 4 g of H2O dropwise to the highly dispersed SnIn@S-1 molecular sieve powder obtained in step (6). After stirring evenly, let it stand for 4 h, then dry it at 120 °C for 12 h, and then grind it. Place it in a muffle furnace and dry it at 550 °C for 12 h to obtain the precursor of PtSnIn@S-1 catalyst powder; (9) Place the obtained precursor of PtSnIn@S-1 catalyst powder in a tubular furnace. In a high-purity H2 atmosphere, heat it at a rate of 2 °C·min -1 to 600 °C and hold for 3 h. Finally, obtain PtSnIn@S-1 catalyst, where the loading amount of Pt is 0.3 wt%, the doping amount of Sn is 0.49 wt%, and the doping amount of In is 0.35 wt%.

[0043] Example 4 (1) Weigh 16.24 g of TPAOH and 16.48 g of TEOS respectively and dissolve them in 7.0 g of deionized water. After stirring for 2.5 h until completely dissolved, a homogeneous solution is obtained; (2) Weigh 24 mg of CrCl3 and dissolve it in 1.0 g of deionized water. After stirring for 1 h, a homogeneous Cr-containing solution is obtained; (3) Weigh 60 mg of Pb(NO3)3 and dissolve it in 1.0 g of deionized water. After stirring for 1 h, a homogeneous Pb-containing solution is obtained; (4) Mix the solutions obtained in steps (1), (2), and (3), and continue to stir for 5 h to form a homogeneous mixed solution. Then, put the above mixed solution into the polytetrafluoroethylene inner lining of a stainless-steel crystallization kettle; (5) Place the stainless-steel crystallization kettle in an oven, heat it from room temperature to 170 °C, and maintain static hydrothermal reaction crystallization for 2 days. After the crystallization is completed, cool it, centrifuge it, dry it at 80 °C for 12 h, then grind it, dry it at 120 °C for 12 h, and finally place it in a muffle furnace and dry it at 550 °C for 12 h to obtain CrPb@S-1 molecular sieve powder; (6) Dissolve the obtained CrPb@S-1 zeolite powder in 1.0 mol / L nitric acid solution, stir in a water bath at 80 °C for 12 h, then wash and centrifuge it multiple times, dry it in an oven at 120 °C for 12 h, and calcine it in a muffle furnace at 600 °C for 12 h to obtain highly dispersed CrPb@S-1 zeolite powder; (7) Weigh 40 mg of H2PtCl6·6H2O and dissolve it in 1.0 g of deionized water. After stirring for 1 h, a homogeneous Pt-containing solution is obtained; (8) Add the solution obtained in step (7) and 4 g of H2O dropwise to the highly dispersed CrPb@S-1 zeolite powder obtained in step (6). After stirring evenly, let it stand for 4 h, then dry it at 120 °C for 12 h, and then grind it and place it in a muffle furnace and dry it at 550 °C for 12 h to obtain the PtCrPb@S-1 catalyst powder precursor; (9) Place the obtained PtCrPb@S-1 catalyst powder precursor in a tubular furnace. In a high-purity H2 atmosphere, heat it at a rate of 2 °C·min -1 to 600 °C and hold for 3 h. Finally, obtain the PtCrPb@S-1 catalyst, where the Pt loading is 0.3 wt%, the Cr doping amount is 0.16 wt%, and the Pb doping amount is 0.63 wt%.

[0044] Example 5 (1) Weigh 16.24 g of TPAOH and 16.48 g of TEOS and dissolve them in 7.0 g of deionized water. After stirring for 2.5 h to completely dissolve them, a homogeneous solution is obtained; (2) Weigh 61 mg of Bi(NO3)3 and dissolve it in 1.0 g of deionized water. After stirring for 1 h, a homogeneous Bi-containing solution is obtained; (3) Weigh 52 mg of Zr(NO3)4 and dissolve it in 1.0 g of deionized water. After stirring for 1 h, a homogeneous Zr-containing solution is obtained; (4) Mix the solutions obtained in steps (1), (2), and (3), and continue to stir for 5 h to form a homogeneous mixed solution. Then, load the above mixed solution into the polytetrafluoroethylene lining of a stainless-steel crystallization kettle; (5) Place the stainless-steel crystallization kettle in an oven, heat it from room temperature to 170 °C, and maintain static hydrothermal reaction crystallization for 2 days. After the crystallization is completed, cool it, centrifuge it, dry it at 80 °C for 12 h, then grind it, dry it at 120 °C for 12 h, and finally place it in a muffle furnace and dry it at 550 °C for 12 h to obtain BiZr@S-1 zeolite powder; (6) Dissolve the obtained BiZr@S-1 molecular sieve powder in 1.0 mol / L nitric acid solution, stir in a water bath at 80 °C for 12 h, then wash and centrifuge it multiple times, dry it in an oven at 120 °C for 12 h, and calcine it in a muffle furnace at 600 °C for 12 h to obtain highly dispersed BiZr@S-1 molecular sieve powder; (7) Weigh 40 mg of H2PtCl6·6H2O and dissolve it in 1.0 g of deionized water. After stirring for 1 h, a uniform Pt-containing solution is obtained; (8) Add the solution obtained in step (7) and 4 g of H2O dropwise to the highly dispersed BiZr@S-1 molecular sieve powder obtained in step (6). After stirring evenly, let it stand for 4 h, then dry it at 120 °C for 12 h, and then grind it. Place it in a muffle furnace and dry it at 550 °C for 12 h to obtain the precursor of PtBiZr@S-1 catalyst powder; (9) Place the obtained precursor of PtBiZr@S-1 catalyst powder in a tubular furnace. In a high-purity H2 atmosphere, heat it to 600 °C at a rate of 2 °C·min -1 and keep it at this temperature for 3 h. Finally, obtain the PtBiZr@S-1 catalyst, where the loading amount of Pt is 0.3 wt%, the doping amount of Bi is 0.64 wt%, and the doping amount of Zr is 0.28 wt%.

[0045] Example 6 (1) Weigh 16.24 g of TPAOH and 16.48 g of TEOS respectively and dissolve them in 7.0 g of deionized water. After stirring for 2.5 h to completely dissolve them, a uniform solution is obtained; (2) Weigh 42 mg of MoCl5 and dissolve it in 1.0 g of deionized water. After stirring for 1 h, a uniform Mo-containing solution is obtained; (3) Weigh 24 mg of VCl3 and dissolve it in 1.0 g of deionized water. After stirring for 1 h, a uniform V-containing solution is obtained; (4) Mix the solutions obtained in steps (1), (2), and (3), and continue to stir for 5 h to form a uniform mixed solution. Then, put the above mixed solution into the polytetrafluoroethylene inner lining of a stainless-steel crystallization kettle; (5) Place the stainless-steel crystallization kettle in an oven, heat it from room temperature to 170 °C, and keep it for static hydrothermal reaction crystallization for 2 days. After the crystallization is completed, cool it, centrifuge it, dry it at 80 °C for 12 h, then grind it, dry it at 120 °C for 12 h, and finally place it in a muffle furnace and dry it at 550 °C for 12 h to obtain MoV@S-1 molecular sieve powder; (6) Dissolve the obtained MoV@S-1 zeolite powder in a 1.0 mol / L nitric acid solution, stir in a water bath at 80 °C for 12 h, then wash and centrifuge it multiple times, dry it in an oven at 120 °C for 12 h, and calcine it in a muffle furnace at 600 °C for 12 h to obtain a highly dispersed MoV@S-1 zeolite powder; (7) Weigh 40 mg of H2PtCl6·6H2O and dissolve it in 1.0 g of deionized water. After stirring for 1 h, a uniform Pt-containing solution is obtained; (8) Add the solution obtained in step (7) and 4 g of H2O dropwise to the highly dispersed MoV@S-1 zeolite powder obtained in step (6). After stirring evenly, let it stand for 4 h, then dry it at 120 °C for 12 h, and then grind it. Place it in a muffle furnace and dry it at 550 °C for 12 h to obtain a PtMoV@S-1 catalyst powder precursor; (9) Place the obtained PtMoV@S-1 catalyst powder precursor in a tubular furnace. In a high-purity H2 atmosphere, heat it at a rate of 2 °C·min -1 to 600 °C and hold for 3 h. Finally, obtain a PtMoV@S-1 catalyst, where the Pt loading is 0.3 wt%, the Mo doping amount is 0.29 wt%, and the V doping amount is 0.16 wt%.

[0046] Example 7 (1) Weigh 16.24 g of TPAOH and 16.48 g of TEOS respectively and dissolve them in 7.0 g of deionized water. After stirring for 2.5 h until completely dissolved, a uniform solution is obtained; (2) Weigh 41 mg of NbCl5 and dissolve it in 1.0 g of deionized water. After stirring for 1 h, a uniform Nb-containing solution is obtained; (3) Weigh 38 mg of LaCl3 and dissolve it in 1.0 g of deionized water. After stirring for 1 h, a uniform La-containing solution is obtained; (4) Mix the solutions obtained in steps (1), (2), and (3), and continue to stir for 5 h to form a uniform mixed solution. Then put the above mixed solution into the polytetrafluoroethylene inner lining of a stainless steel crystallization kettle; (5) Place the stainless steel crystallization kettle in an oven, heat it from room temperature to 170 °C, and maintain static hydrothermal reaction crystallization for 2 days. After the crystallization is completed, cool it, centrifuge it, dry it at 80 °C for 12 h, then grind it, dry it at 120 °C for 12 h, and finally place it in a muffle furnace and dry it at 550 °C for 12 h to obtain MoV@S-1 zeolite powder; (6) Dissolve the obtained NbLa@S-1 molecular sieve powder in 1.0 mol / L nitric acid solution, stir in a water bath at 80 °C for 12 h, then wash and centrifuge it multiple times, dry it in an oven at 120 °C for 12 h, and calcine it in a muffle furnace at 600 °C for 12 h to obtain highly dispersed NbLa@S-1 molecular sieve powder; (7) Weigh 40 mg of H2PtCl6·6H2O and dissolve it in 1.0 g of deionized water. After stirring for 1 h, a homogeneous Pt-containing solution is obtained; (8) Add the solution obtained in step (7) and 4 g of H2O dropwise to the highly dispersed NbLa@S-1 molecular sieve powder obtained in step (6). After stirring evenly, let it stand for 4 h, then dry it at 120 °C for 12 h, and then grind it. Place it in a muffle furnace and dry it at 550 °C for 12 h to obtain the PtNbLa@S-1 catalyst powder precursor; (9) Place the obtained PtNbLa@S-1 catalyst powder precursor in a tubular furnace. In a high-purity H2 atmosphere, heat it at a rate of 2 °C·min -1 to 600 °C and hold for 3 h. Finally, obtain the PtNbLa@S-1 catalyst, where the Pt loading is 0.3 wt%, the Nb doping amount is 0.28 wt%, and the La doping amount is 0.43 wt%.

[0047] Example 8 (1) Weigh 16.24 g of TPAOH and 16.48 g of TEOS respectively and dissolve them in 7.0 g of deionized water. After stirring for 2.5 h until completely dissolved, a homogeneous solution is obtained; (2) Weigh 35 mg of SbCl3 and dissolve it in 1.0 g of deionized water. After stirring for 1 h, a homogeneous Sb-containing solution is obtained; (3) Weigh 24 mg of TiCl3 and dissolve it in 1.0 g of deionized water. After stirring for 1 h, a homogeneous Ti-containing solution is obtained; (4) Mix the solutions obtained in steps (1), (2), and (3), and continue to stir for 5 h to form a homogeneous mixed solution. Then, put the above mixed solution into the polytetrafluoroethylene lining of a stainless-steel crystallization kettle; (5) Place the stainless-steel crystallization kettle in an oven, heat it from room temperature to 170 °C, and maintain static hydrothermal reaction crystallization for 2 days. After the crystallization is completed, cool it, centrifuge it, dry it at 80 °C for 12 h, then grind it, dry it at 120 °C for 12 h, and finally place it in a muffle furnace and dry it at 550 °C for 12 h to obtain SbTi@S-1 molecular sieve powder; (6) The obtained SbTi@S-1 molecular sieve powder was dissolved in a 1.0 mol / L nitric acid solution, stirred in a water bath at 80 °C for 12 h, then washed and centrifuged multiple times, dried in an oven at 120 °C for 12 h, and calcined in a muffle furnace at 600 °C for 12 h to obtain highly dispersed SbTi@S-1 molecular sieve powder; (7) Weighed 40 mg of H2PtCl6·6H2O and dissolved it in 1.0 g of deionized water. After stirring for 1 h, a homogeneous Pt-containing solution was obtained; (8) The solution obtained in step (7) and 4 g of H2O were added dropwise to the highly dispersed SbTi@S-1 molecular sieve powder obtained in step (6). After stirring evenly, it was left standing for 4 h, then dried at 120 °C for 12 h, and then ground. After that, it was placed in a muffle furnace and dried at 550 °C for 12 h to obtain the PtSbTi@S-1 catalyst powder precursor; (9) The obtained PtSbTia@S-1 catalyst powder precursor was placed in a tubular furnace. In a high-purity H2 atmosphere, it was heated to 600 °C at a rate of 2 °C·min -1 and held for 3 h. Finally, the PtSbTi@S-1 catalyst was obtained, where the Pt loading was 0.3 wt%, the Sb doping amount was 0.37 wt%, and the Ti doping amount was 0.15 wt%.

[0048] Figure 1 XRD patterns of the catalysts prepared in Examples 1 - 8. As can be seen from the figure, no crystal diffraction peaks attributed to metal particles were observed in the range of 2θ = 5° - 60° for the obtained Pt-based catalysts, indicating that the metal components exist in a highly dispersed state on the surface of the molecular sieve support.

[0049] Figure 2 SEM images of the catalysts prepared in Examples 1 - 8. As can be seen from the figure, the Pt-based catalysts prepared in the examples all maintained the original polyhedral structure of S-1, indicating that the added multiple heteroatoms did not affect the morphology of the molecular sieve.

[0050] Figure 3 HADDF-STEM images of the PtSnIn@S-1 catalyst prepared in Example 3. As can be seen from the figure, the metal particles on the surface of the catalyst are very evenly dispersed.

[0051] The catalysts prepared in the comparative examples and examples were formed into 20 - 60 mesh granular catalysts, and then filled in a fixed-bed reactor equipped with a quartz tube with an inner diameter of 12 mm. The catalyst was maintained in the constant temperature range of the heating furnace of the fixed-bed reactor; then, the catalyst was heated to 600 °C at a rate of 2 °C·min in an H2 atmosphere -1 and held for 3 h, and then at a rate of 2 °C·min -1The rate was increased to the reaction temperature of 630 °C, and pure propane gas was introduced (WHSV = 8.0 h -1 ), samples were taken at 1 h and 48 h of the reaction respectively, the reaction gas was detected by gas chromatography, and the propane conversion and propylene selectivity were calculated. The results are shown in Table 1.

[0052] Table 1 Comparison of high-temperature catalytic reaction performance of different Pt-based catalysts

[0053] It can be seen from the catalytic performance results in Table 1 that compared with the Pt-based catalysts prepared using Al-containing zeolite ZSM-5 as the carrier in Comparative Examples 1 and 2, and the pure silica molecular sieve-supported Pt-based catalysts doped with single heteroatoms in Comparative Examples 3 and 4, the propane conversion and propylene selectivity of the pure silica molecular sieve-supported Pt-based catalysts prepared by multi-heteroatom doping in the Examples have been significantly improved, with their propylene selectivity being greater than 98%. Moreover, the catalyst maintained excellent propane conversion and propylene selectivity and showed almost no deactivation phenomenon after continuous reaction at high temperature (>600 °C) for 48 h, indicating that the catalytic activity and high-temperature stability of the obtained Pt-based catalyst can be greatly improved by multi-heteroatom doping of pure silica molecular sieve.

[0054] All of the above fully illustrate that by doping highly dispersed multi-heteroatoms on the pure silica molecular sieve support, the obtained Pt-based catalyst can possess more excellent high-temperature propane dehydrogenation catalytic performance. This is because this method promotes the more uniform dispersion of the active component Pt on the catalyst surface, thereby increasing the active sites of the catalyst and effectively enhancing the catalytic activity. At the same time, the highly dispersed multi-heteroatoms doped on the pure silica molecular sieve can firmly stabilize the Pt particles, prevent the Pt particles from agglomerating at high temperature, thus maintaining the uniform distribution of the Pt species and significantly enhancing the high-temperature stability of the catalyst. After a comprehensive comparison with existing similar Pt-based propane dehydrogenation catalysts, it is found that the catalytic performance of the Pt-based catalyst prepared by the method of the present invention significantly exceeds the currently reported catalysts, providing strong support for the future design and application fields of high-temperature catalysts.

[0055] The above are only the preferred embodiments of the present invention, and all equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope of the present invention.

Claims

1. A Pt-based catalyst supported on a multi-heteroatom-doped pure silica molecular sieve, characterized in that: The catalyst uses a pure silica molecular sieve doped with multiple heteroatoms as the carrier and Pt as the active metal component; The heteroatoms are selected from any two or more of Ce, Co, Cu, Cr, Bi, Fe, Ni, Ga, V, Sc, Y, La, W, Sb, Pb, Sn, Nb, Mn, Mo, V, Ti, Zn, In, Zr, Ge.

2. The Pt-based catalyst supported on a multi-heteroatom-doped pure silica molecular sieve according to claim 1, wherein: Based on the total mass of the catalyst, the total doping amount of the heteroatoms is 0.01 - 1.00 wt%, and the loading amount of the active metal component Pt is 0.01 - 1.00 wt%.

3. A preparation method of a Pt-based catalyst supported on a multi-heteroatom-doped pure silica molecular sieve as described in claim 1, characterized in that: First, prepare a pure silica molecular sieve doped with multiple heteroatoms through hydrothermal crystallization and pickling, and then use the impregnation method to load the active metal component Pt onto the pure silica molecular sieve doped with multiple heteroatoms to obtain the catalyst.

4. The preparation method according to claim 3, characterized in that, It includes the following steps: (1) Preparation of the pure silica molecular sieve doped with multiple heteroatoms: Fully mix and stir the silicon source, template agent, water, and heteroatom compound to obtain a homogeneous mixed solution. Then, after subjecting this mixed solution to hydrothermal crystallization, centrifugation, drying, grinding, secondary drying, and calcination, dissolve it in a nitric acid solution, and then through high-temperature stirring, washing and centrifugation, drying, and calcination, obtain the pure silica molecular sieve doped with multiple heteroatoms; (2) Preparation of the supported Pt-based catalyst: Load the Pt compound onto the pure silica molecular sieve doped with multiple heteroatoms prepared above by the impregnation method, and subject the product to drying, grinding, calcination, and reduction to finally obtain the catalyst.

5. The preparation method according to claim 4, characterized in that: Based on the content of SiO2 in the silicon source, the molar ratio of the silicon source, template agent, water, and total amount of heteroatoms used in step (1) is 1:(0.10 - 1.00):(1 - 50):(0.0001 - 0.001).

6. The preparation method according to claim 4 or 5, characterized in that: The silicon source is any one or several of fumed silica, tetraethyl orthosilicate, sodium silicate, silica sol; The template agent is any one or several of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetramethylammonium bromide, tetrabutylammonium bromide; The heteroatom compound is an oxide, chloride, and / or nitrate of any two or more of Ce, Co, Cu, Cr, Bi, Fe, Ni, Ga, V, Sc, Y, La, W, Sb, Pb, Sn, Nb, Mn, Mo, V, Ti, Zn, In, Zr, Ge.

7. The preparation method according to claim 4, characterized in that: In step (1), the temperature of the hydrothermal crystallization is 80 - 180 °C, and the time is 8 - 80 h; the temperature of the drying is 80 - 180 °C, and the time is 8 - 18 h; the temperature of the calcination is 180 - 800 °C, and the time is 8 - 18 h; the concentration of the nitric acid solution is 0.5 - 2.0 mol / L; the temperature of the high-temperature stirring is 80 - 180 °C, and the time is 8 - 18 h.

8. The preparation method according to claim 4, characterized in that: In step (2), the Pt compound is any one or several of PtCl2, PtCl4, H2PtCl6·6H2O, Pt(NH3)4(OH)2, Pt(NH3)4Cl2·H2O.

9. The preparation method according to claim 4, characterized in that: In step (2), the treatment time using the impregnation method is 2 to 10 h; the drying temperature is 80 to 180 °C, and the time is 8 to 18 h; the calcination temperature is 180 to 800 °C, and the time is 8 to 18 h; the reduction is carried out at 180 to 800 °C for 8 to 18 h under a hydrogen atmosphere.

10. Use of a polyheteroatom-doped pure silica molecular sieve-supported Pt-based catalyst as described in claim 1 in the propane dehydrogenation reaction.

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