A preparation method of a Pt-based molecular sieve catalyst for dehydrogenation of propane to propylene
By preparing a Pt-based molecular sieve catalyst for propane dehydrogenation to propylene, the mechanical strength and molding problems of the catalyst in industrial applications were solved, achieving high efficiency and stability, suitable for industrial plants, and possessing the potential for large-scale production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- FUZHOU UNIV
- Filing Date
- 2026-04-03
- Publication Date
- 2026-07-03
AI Technical Summary
Existing propane dehydrogenation catalysts suffer from problems in industrial applications, such as large bed pressure drop, uneven airflow distribution, severe dust entrainment, and insufficient mechanical strength to meet industrial loading, unloading, and operation requirements. Furthermore, existing molding methods are costly and complex, making it difficult to achieve large-scale promotion.
Using in-situ hydrothermal synthesis of all-silica MFI molecular sieve as a carrier, active component Pt and auxiliary metal were introduced by impregnation, and binder, solvent and lubricant were added. After mixing and extrusion molding, Pt-based molecular sieve catalyst for propane dehydrogenation to propylene was prepared.
It achieves a synergistic effect between the high mechanical properties and intrinsic catalytic properties of the catalyst, maintains the pore connectivity and activity of the catalyst, meets the requirements of long life and low energy consumption of industrial plants, and the process is simple and easy to scale up industrially.
Smart Images
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Abstract
Description
Technical Field
[0001] This invention relates to the field of industrial catalyst preparation, and more particularly to a method for preparing a Pt-based molecular sieve catalyst for propane dehydrogenation to propylene. Background Technology
[0002] Propylene is one of the world's most in-demand basic chemical raw materials, with annual consumption exceeding 140 million tons. It is a key precursor for the production of many high-value-added products such as polypropylene, acrylonitrile, and propylene oxide. Compared to traditional propylene production routes, propane dehydrogenation (PDH) technology has significant advantages such as high propane conversion rate, high propylene yield, and low production cost, aligning with the concept of green and low-carbon development. It has become a key technological path for dedicated propylene production and achieving raw material diversification. However, the industrial economics and market competitiveness of this technology are highly dependent on the catalytic performance of its core component—the catalyst. Therefore, developing novel dehydrogenation catalysts with high activity, high propylene selectivity, and high stability is crucial for reducing PDH production costs and enhancing technological competitiveness, and it is also a core challenge that catalysis science and the petrochemical industry urgently need to overcome.
[0003] In recent years, significant progress has been made in the research and development of propane dehydrogenation catalysts. Researchers both domestically and internationally have focused on Pt-based active components, employing strategies such as support modification, additive introduction, and active site regulation to improve catalyst activity, selectivity, and resistance to carbon deposition. However, the catalytic performance of these catalysts is mostly evaluated in laboratory fixed-bed conditions using powdered catalysts. Current industrial propane dehydrogenation units commonly employ moving-bed or fluidized-bed processes, placing higher demands on catalyst geometry (e.g., spherical, strip-shaped) and mechanical strength. Powdered catalysts must undergo shaping to meet industrial application standards.
[0004] Several catalyst molding-related schemes have been disclosed in the prior art, but all have obvious limitations. For example, patent CN121249272A discloses a binder for catalyst molding, which introduces a multi-component system including magnesium chloride, magnesium oxide, sodium carboxymethyl cellulose, EDTA, and nano-hydroxyapatite-modified polyester. Although it has a certain effect on molding, the multi-component system may lead to increased costs, and the high-temperature decomposition of organic matter may affect structural stability. Its universality needs further verification. Patent CN119793526A proposes a method for treating SAPO-34 molecular sieve catalysts. By removing blockages in the micropores through acid treatment and crystallization processes, it significantly improves the selectivity and catalyst life of methanol-to-olefins reaction. However, acid treatment can easily damage the molecular sieve framework structure, while the high-temperature crystallization process brings problems such as high energy consumption and difficulty in cost control. Patent CN114425327A discloses a method for preparing a propane dehydrogenation catalyst. This method involves mixing a platinum-containing precursor solution with boehmite trihydrate and specific additives to form a sol, which is then dropped into a molding column to obtain a spherical catalyst. This method has advantages such as uniform distribution of active components and a short process flow. However, it requires high precision in controlling sol viscosity, surface tension, and other physical properties. Controlling the spherical size depends on precise dropping rates and column heights, among other complex operating conditions. During industrial scale-up, problems such as poor sphericity and wide particle size distribution easily arise, hindering its large-scale application. Therefore, developing a simple and low-cost method for molding Pt-based molecular sieve catalysts for propane dehydrogenation, and obtaining molded catalysts with both high mechanical strength and high catalytic activity that meet the requirements of industrial moving bed devices, has become a pressing technical need in this field. Summary of the Invention
[0005] This invention aims to address the technical problems encountered by existing molecular sieve powder catalysts when directly applied to fixed-bed, moving-bed, or fluidized-bed reactors, such as large bed pressure drop, uneven airflow distribution, severe dust entrainment, and insufficient mechanical strength to meet wear requirements during industrial loading, unloading, and operation. To this end, this invention provides a method for preparing a Pt-based molecular sieve catalyst for propane dehydrogenation to propylene. This method uses an all-silica MFI molecular sieve synthesized in situ via hydrothermal synthesis as a support. The active component Pt and auxiliary metals are introduced through impregnation, followed by the addition of a binder, solvent, plasticizer, and lubricant. After mixing and homogenization, the mixture is extruded to obtain the Pt-based molecular sieve catalyst for propane dehydrogenation to propylene. This method can impart excellent mechanical properties to the catalyst while maximally preserving the intrinsic catalytic activity of the molecular sieve and the pore structure of the support, thereby achieving the preparation of a high-performance propane dehydrogenation to propylene catalyst.
[0006] To achieve the above objectives, the present invention adopts the following technical solution:
[0007] A method for preparing a Pt-based molecular sieve catalyst for propane dehydrogenation to propylene involves using a molecular sieve as a carrier, first introducing active metal Pt and auxiliary metals through an impregnation method, then adding binders, solvents, plasticizers, and lubricants, mixing them evenly, extruding them into shape, and finally drying and calcining them to obtain the Pt-based molecular sieve catalyst for propane dehydrogenation to propylene.
[0008] Furthermore, the preparation method of the above-mentioned Pt-based molecular sieve catalyst for propane dehydrogenation to propylene includes the following steps:
[0009] (1) Preparation of molecular sieve support
[0010] The template agent and silicon source were dissolved in deionized water to obtain a homogeneous mixed solution. The homogeneous mixed solution was added to a stainless steel crystallization vessel with a polytetrafluoroethylene liner and static hydrothermal crystallization was performed. After crystallization, the mixture was cooled, centrifuged, the precipitate was collected and dried, ground, dried, and calcined to obtain an all-silicon molecular sieve support.
[0011] The amount of feed is based on the molar amount of SiO2 contained in the silicon source, and the molar ratio of each component is: template agent: silicon source = 0.1~1.1:1, deionized water: silicon source = 3~20:1;
[0012] (2) Formation of Pt-based molecular sieve catalysts
[0013] Weigh out a whole silica molecular sieve support, add an active metal Pt solution and an auxiliary metal solution to it, impregnate at room temperature, then add a binder, a peptizing agent, a plasticizer and a lubricant, and knead the mixture in a kneader until it forms an extrudable paste, then extrude it into shape, and after drying and calcining, obtain a propane dehydrogenation to propylene Pt-based molecular sieve catalyst.
[0014] The feed amount is based on the mass of the all-silica molecular sieve carrier, and the mass ratio of each component is as follows: active metal Pt: all-silica molecular sieve carrier = 0.003~0.009:1, auxiliary metal: all-silica molecular sieve carrier = 0.002~0.02:1, binder: all-silica molecular sieve carrier = 0~0.7:1, adhesive solvent: all-silica molecular sieve carrier = 0~0.04:1, plasticizer: all-silica molecular sieve carrier = 0.01~0.04:1, lubricant: all-silica molecular sieve carrier = 0.1~0.3:1.
[0015] Furthermore, in step (1), the template agent is any one or more of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetramethylammonium bromide, and tetrabutylammonium bromide, and the silicon source is any one or more of silica sol, silica fume, and tetraethyl orthosilicate.
[0016] Furthermore, in step (2), the active metal component Pt solution is any one or more of PtCl2 solution, PtCl4 solution, H2PtCl6·6H2O solution, Pt(NH3)4(OH)2 solution, and Pt(NH3)4Cl2·H2O solution, and the auxiliary metal solution is any one or more of SnCl4·5H2O solution, GeCl4 solution, FeCl3·6H2O solution, MnCl2 solution, CoCl2·6H2O solution, ZnCl2 solution, CuCl2·2H2O solution, and GaCl3 solution.
[0017] Furthermore, in step (2), the adhesive is any one or more of silica sol, aluminum sol, and silica-alumina sol; the adhesive solvent is any one or more of concentrated sulfuric acid, concentrated nitric acid, and concentrated hydrochloric acid; the plasticizer is any one or more of wheat starch, sweet potato starch, methylcellulose, and guar gum; and the lubricant is any one or more of glycerin, vegetable oil, and deionized water.
[0018] Furthermore, in step (1), the crystallization temperature is 80~180℃ and the time is 8~80h; the drying temperature is 80~180℃ and the time is 2~10h; the calcination temperature is 180~800℃ and the time is 2~10h.
[0019] Furthermore, in step (2), the soaking time is 1~5h; the drying temperature is 80~180℃ and the time is 2~10h; the roasting temperature is 180~800℃ and the time is 2~10h.
[0020] A Pt-based molecular sieve catalyst for propane dehydrogenation to propylene is prepared by the above-described method.
[0021] The above-mentioned Pt-based molecular sieve catalyst for propane dehydrogenation to propylene is applied in the catalytic reaction of propane dehydrogenation to propylene.
[0022] Furthermore, the application method is as follows: First, a certain mass of Pt-based molecular sieve catalyst for propane dehydrogenation to propylene is weighed and packed into a fixed-bed reactor with an inner diameter of 12 mm quartz tube, ensuring that the catalyst bed is located in the isothermal zone of the reactor heater to guarantee a uniform and stable reaction temperature; then, H2 is introduced to raise the reactor temperature to 100~800℃ for pretreatment for 1~3 hours to ensure complete catalyst activation. After pretreatment, the reactor temperature is adjusted to the target reaction temperature (100~800℃) for propane dehydrogenation to propylene, and the reaction pressure is atmospheric pressure. Finally, pure propane reaction gas is introduced, and the propane mass hourly space velocity (WHSV) is controlled at 4~2000 h⁻¹. -1 The reaction of propane dehydrogenation to propylene is carried out.
[0023] The significant advantages of this invention are:
[0024] This invention provides a method for preparing a Pt-based molecular sieve catalyst for propane dehydrogenation to propylene. This method achieves a high degree of synergy between the catalyst's mechanical properties and intrinsic catalytic performance, maximizing the preservation of the catalyst's intrinsic activity and pore connectivity. The prepared catalyst not only possesses excellent catalytic activity and propylene selectivity but also exhibits long-term stable catalytic performance, fully meeting the industrial plant's requirements for long catalyst life, low energy consumption, and high yield. The method of this invention is simple, with controllable parameters, and is easily scaled up for industrial production. It provides a reliable and feasible technical solution for the large-scale preparation of high-performance propane dehydrogenation to propylene catalysts, contributing to the industrial upgrading of PDH technology. Attached Figure Description
[0025] Figure 1 The X-ray diffraction (XRD) patterns of the catalysts in Comparative Examples 1-2 and Examples 1-8 are shown.
[0026] Figure 2 The images show actual photos of the catalysts used in Comparative Examples 1-2 and Examples 1-2.
[0027] Figure 3 The figures show the catalytic performance of the catalysts in Comparative Examples 1-2 and Examples 1-2. Detailed Implementation
[0028] To make the content of this invention easier to understand, the technical solution of this invention will be further described below with reference to specific embodiments, but this invention is not limited thereto.
[0029] Comparative Example 1:
[0030] A method for preparing a Pt-based molecular sieve catalyst for propane dehydrogenation to propylene includes the following steps:
[0031] (1) Weigh 162.4g of tetrapropylammonium hydroxide (TPAOH) and 164.8g of tetraethyl orthosilicate (TEOS) and dissolve them in 70.0g of deionized water. Stir at room temperature for 3h until completely dissolved to obtain a homogeneous mixed solution.
[0032] (2) The homogeneous mixed solution from step (1) was added to a stainless steel crystallization vessel with a polytetrafluoroethylene liner and statically hydrothermally crystallized at 170°C for 48 hours. After crystallization, the mixture was naturally cooled to room temperature. The obtained product was centrifuged, the precipitate was collected and dried at 80°C for 3 hours, then ground to 200 mesh, dried at 120°C for 3 hours, and finally calcined in an air atmosphere at 550°C for 4 hours to obtain the all-silicon S-1 molecular sieve support.
[0033] (3) Weigh 0.56g H2PtCl6·6H2O and dissolve it in 2.0g deionized water. Stir at room temperature for 1h until completely dissolved to obtain a Pt-containing solution.
[0034] (4) Weigh 0.76g SnCl4·5H2O and dissolve it in 2.0g deionized water. Stir at room temperature for 1h until completely dissolved to obtain a Sn-containing solution.
[0035] (5) Weigh 70.0g of the all-silica S-1 molecular sieve support prepared in step (2), add all of the Pt-containing solution prepared in step (3) and the Sn-containing solution prepared in step (4), and soak at room temperature for 3h. Then add 2.0g of 65wt% concentrated nitric acid aqueous solution, 0.8g of 200-mesh unmodified wheat starch with a moisture content of 10wt% and 20.0g of deionized water. The mixture is kneaded evenly at room temperature at a speed of 20rpm in a kneader (takes 15min) until a paste-like material is formed. Finally, it is extruded into a cylindrical strip with a diameter of 2.0mm. The obtained cylindrical strip is dried at 120℃ for 3h, and then placed in a muffle furnace at 550℃ and calcined in air atmosphere for 4h to obtain the propane dehydrogenation to propylene Pt-based molecular sieve catalyst, which is denoted as sample A.
[0036] Comparative Example 2:
[0037] A method for preparing a Pt-based molecular sieve catalyst for propane dehydrogenation to propylene includes the following steps:
[0038] (1) Weigh 162.4g TPAOH and 164.8g TEOS and dissolve them in 70.0g deionized water. Stir at room temperature for 3 hours until completely dissolved to obtain a homogeneous mixed solution.
[0039] (2) The homogeneous mixed solution from step (1) was added to a stainless steel crystallization vessel with a polytetrafluoroethylene liner and statically hydrothermally crystallized at 170°C for 48 hours. After crystallization, the mixture was naturally cooled to room temperature. The obtained product was centrifuged, the precipitate was collected and dried at 80°C for 3 hours, then ground to 200 mesh, dried at 120°C for 3 hours, and finally calcined in an air atmosphere at 550°C for 4 hours to obtain the all-silicon S-1 molecular sieve support.
[0040] (3) Weigh 0.56g H2PtCl6·6H2O and dissolve it in 2.0g deionized water. Stir at room temperature for 1h until completely dissolved to obtain a Pt-containing solution.
[0041] (4) Weigh 0.76g SnCl4·5H2O and dissolve it in 2.0g deionized water. Stir at room temperature for 1h until completely dissolved to obtain a Sn-containing solution.
[0042] (5) Weigh 70.0g of the all-silica S-1 molecular sieve support prepared in step (2), add all of the Pt-containing solution prepared in step (3) and the Sn-containing solution prepared in step (4) into it, and soak at room temperature for 3h. Then add 27.3g of 30wt% silica sol aqueous solution, 0.8g of 200-mesh unmodified wheat starch with a moisture content of 10wt% and 20.0g of deionized water. The mixture is kneaded evenly at room temperature at a speed of 20rpm in a kneader (takes 15min) until it forms an extrudable paste. Finally, it is extruded into a cylindrical strip with a diameter of 2.0mm. The obtained cylindrical strip is dried at 120℃ for 3h, and then placed in a muffle furnace at 550℃ and calcined in air atmosphere for 4h to obtain the propane dehydrogenation to propylene Pt-based molecular sieve catalyst, which is denoted as sample B.
[0043] Example 1:
[0044] A method for preparing a Pt-based molecular sieve catalyst for propane dehydrogenation to propylene includes the following steps:
[0045] (1) Weigh 162.4g TPAOH and 164.8g TEOS and dissolve them in 70.0g deionized water. Stir at room temperature for 3 hours until completely dissolved to obtain a homogeneous mixed solution.
[0046] (2) The homogeneous mixed solution from step (1) was added to a stainless steel crystallization vessel with a polytetrafluoroethylene liner and statically hydrothermally crystallized at 170°C for 48 hours. After crystallization, the mixture was naturally cooled to room temperature. The obtained product was centrifuged, the precipitate was collected and dried at 80°C for 3 hours, then ground to 200 mesh, dried at 120°C for 3 hours, and finally calcined in an air atmosphere at 550°C for 4 hours to obtain the all-silicon S-1 molecular sieve support.
[0047] (3) Weigh 0.56g H2PtCl6·6H2O and dissolve it in 2.0g deionized water. Stir at room temperature for 1h until completely dissolved to obtain a Pt-containing solution.
[0048] (4) Weigh 0.76g SnCl4·5H2O and dissolve it in 2.0g deionized water. Stir at room temperature for 1h until completely dissolved to obtain a Sn-containing solution.
[0049] (5) Weigh 70.0g of the all-silica S-1 molecular sieve support prepared in step (2), add all of the Pt-containing solution prepared in step (3) and the Sn-containing solution prepared in step (4) into it, and soak at room temperature for 3h. Then add 27.3g of 30wt% silica sol aqueous solution, 2.0g of 65wt% concentrated nitric acid aqueous solution, 0.8g of 200-mesh unmodified wheat starch with a moisture content of 10wt% and 20.0g of deionized water. The mixture is kneaded evenly at room temperature at a speed of 20rpm in a kneader (takes 15min) until a paste-like material is formed. Finally, it is extruded into a cylindrical strip with a diameter of 2.0mm. The obtained cylindrical strip is dried at 120℃ for 3h, and then placed in a muffle furnace at 550℃ and calcined in air atmosphere for 4h to obtain the propane dehydrogenation to propylene Pt-based molecular sieve catalyst, which is denoted as sample C.
[0050] Example 2:
[0051] A method for preparing a Pt-based molecular sieve catalyst for propane dehydrogenation to propylene includes the following steps:
[0052] (1) Weigh 162.4g TPAOH and 164.8g TEOS and dissolve them in 70.0g deionized water. Stir at room temperature for 3 hours until completely dissolved to obtain a homogeneous mixed solution.
[0053] (2) The homogeneous mixed solution from step (1) was added to a stainless steel crystallization vessel with a polytetrafluoroethylene liner and statically hydrothermally crystallized at 170°C for 48 hours. After crystallization, the mixture was naturally cooled to room temperature. The obtained product was centrifuged, the precipitate was collected and dried at 80°C for 3 hours, then ground to 200 mesh, dried at 120°C for 3 hours, and finally calcined in an air atmosphere at 550°C for 4 hours to obtain the all-silicon S-1 molecular sieve support.
[0054] (3) Weigh 0.56g H2PtCl6·6H2O and dissolve it in 2.0g deionized water. Stir at room temperature for 1h until completely dissolved to obtain a Pt-containing solution.
[0055] (4) Weigh 0.46g of GeCl4 and dissolve it in 2.0g of deionized water. Stir at room temperature for 1h until completely dissolved to obtain a Ge-containing solution.
[0056] (5) Weigh 70.0g of the all-silica S-1 molecular sieve support prepared in step (2), add all of the Pt-containing solution prepared in step (3) and the Ge-containing solution prepared in step (4), and soak at room temperature for 3h. Then add 27.3g of 30wt% silica sol aqueous solution, 2.0g of 65wt% concentrated nitric acid aqueous solution, 0.8g of 200-mesh unmodified wheat starch with a moisture content of 10wt% and 20.0g of deionized water. The mixture is kneaded evenly at room temperature at a speed of 20rpm in a kneader (takes 15min) until a paste-like material is formed. Finally, it is extruded into a cylindrical strip with a diameter of 2.0mm. The obtained cylindrical strip is dried at 120℃ for 3h, and then placed in a muffle furnace at 550℃ and calcined in air atmosphere for 4h to obtain the propane dehydrogenation to propylene Pt-based molecular sieve catalyst, which is denoted as sample D.
[0057] Example 3:
[0058] A method for preparing a Pt-based molecular sieve catalyst for propane dehydrogenation to propylene includes the following steps:
[0059] (1) Weigh 162.4g TPAOH and 164.8g TEOS and dissolve them in 70.0g deionized water. Stir at room temperature for 3 hours until completely dissolved to obtain a homogeneous mixed solution.
[0060] (2) The homogeneous mixed solution from step (1) was added to a stainless steel crystallization vessel with a polytetrafluoroethylene liner and statically hydrothermally crystallized at 170°C for 48 hours. After crystallization, the mixture was naturally cooled to room temperature. The obtained product was centrifuged, the precipitate was collected and dried at 80°C for 3 hours, then ground to 200 mesh, dried at 120°C for 3 hours, and finally calcined in an air atmosphere at 550°C for 4 hours to obtain the all-silicon S-1 molecular sieve support.
[0061] (3) Weigh 0.56g H2PtCl6·6H2O and dissolve it in 2.0g deionized water. Stir at room temperature for 1h until completely dissolved to obtain a Pt-containing solution.
[0062] (4) Weigh 0.59g FeCl3·6H2O and dissolve it in 2.0g deionized water. Stir at room temperature for 1h until completely dissolved to obtain a Fe-containing solution.
[0063] (5) Weigh 70.0g of the all-silica S-1 molecular sieve support prepared in step (2), add all of the Pt-containing solution prepared in step (3) and the Fe-containing solution prepared in step (4) into it, and soak at room temperature for 3h. Then add 27.3g of 30wt% silica sol aqueous solution, 2.0g of 65wt% concentrated nitric acid aqueous solution, 0.8g of 200-mesh unmodified wheat starch with a moisture content of 10wt% and 20.0g of deionized water. The mixture is kneaded evenly at room temperature at a speed of 20rpm in a kneader (takes 15min) until a paste-like material is formed. Finally, it is extruded into a cylindrical strip with a diameter of 2.0mm. The obtained cylindrical strip is dried at 120℃ for 3h, and then placed in a muffle furnace at 550℃ and calcined in air atmosphere for 4h to obtain the propane dehydrogenation to propylene Pt-based molecular sieve catalyst, which is denoted as sample E.
[0064] Example 4:
[0065] A method for preparing a Pt-based molecular sieve catalyst for propane dehydrogenation to propylene includes the following steps:
[0066] (1) Weigh 162.4g TPAOH and 164.8g TEOS and dissolve them in 70.0g deionized water. Stir at room temperature for 3 hours until completely dissolved to obtain a homogeneous mixed solution.
[0067] (2) The homogeneous mixed solution from step (1) was added to a stainless steel crystallization vessel with a polytetrafluoroethylene liner and statically hydrothermally crystallized at 170°C for 48 hours. After crystallization, the mixture was naturally cooled to room temperature. The obtained product was centrifuged, the precipitate was collected and dried at 80°C for 3 hours, then ground to 200 mesh, dried at 120°C for 3 hours, and finally calcined in an air atmosphere at 550°C for 4 hours to obtain the all-silicon S-1 molecular sieve support.
[0068] (3) Weigh 0.56g H2PtCl6·6H2O and dissolve it in 2.0g deionized water. Stir at room temperature for 1h until completely dissolved to obtain a Pt-containing solution.
[0069] (4) Weigh 0.27g of MnCl2 and dissolve it in 2.0g of deionized water. Stir at room temperature for 1h until completely dissolved to obtain a solution containing Mn.
[0070] (5) Weigh 70.0g of the all-silica S-1 molecular sieve support prepared in step (2), add all of the Pt-containing solution prepared in step (3) and the Mn-containing solution prepared in step (4) into it, and soak at room temperature for 3h. Then add 27.3g of 30wt% silica sol aqueous solution, 2.0g of 65wt% concentrated nitric acid aqueous solution, 0.8g of 200-mesh unmodified wheat starch with a moisture content of 10wt% and 20.0g of deionized water. The mixture is kneaded evenly at room temperature at a speed of 20rpm in a kneader (takes 15min) until a paste-like material is formed. Finally, it is extruded into a cylindrical strip with a diameter of 2.0mm. The obtained cylindrical strip is dried at 120℃ for 3h, and then placed in a muffle furnace at 550℃ and calcined in air atmosphere for 4h to obtain the propane dehydrogenation to propylene Pt-based molecular sieve catalyst, which is denoted as sample F.
[0071] Example 5:
[0072] A method for preparing a Pt-based molecular sieve catalyst for propane dehydrogenation to propylene includes the following steps:
[0073] (1) Weigh 162.4g TPAOH and 164.8g TEOS and dissolve them in 70.0g deionized water. Stir at room temperature for 3 hours until completely dissolved to obtain a homogeneous mixed solution.
[0074] (2) The homogeneous mixed solution from step (1) was added to a stainless steel crystallization vessel with a polytetrafluoroethylene liner and statically hydrothermally crystallized at 170°C for 48 hours. After crystallization, the mixture was naturally cooled to room temperature. The obtained product was centrifuged, the precipitate was collected and dried at 80°C for 3 hours, then ground to 200 mesh, dried at 120°C for 3 hours, and finally calcined in an air atmosphere at 550°C for 4 hours to obtain the all-silicon S-1 molecular sieve support.
[0075] (3) Weigh 0.56g H2PtCl6·6H2O and dissolve it in 2.0g deionized water. Stir at room temperature for 1h until completely dissolved to obtain a Pt-containing solution.
[0076] (4) Weigh 0.51g CoCl2·6H2O and dissolve it in 2.0g deionized water. Stir at room temperature for 1h until completely dissolved to obtain a Co-containing solution.
[0077] (5) Weigh 70.0g of the all-silica S-1 molecular sieve support prepared in step (2), add all of the Pt-containing solution prepared in step (3) and the Co-containing solution prepared in step (4), and soak at room temperature for 3h. Then add 27.3g of 30wt% silica sol aqueous solution, 2.0g of 65wt% concentrated nitric acid aqueous solution, 0.8g of 200-mesh unmodified wheat starch with a moisture content of 10wt% and 20.0g of deionized water. The mixture is kneaded evenly at room temperature at a speed of 20rpm in a kneader (takes 15min) until a paste-like material is formed. Finally, it is extruded into a cylindrical strip with a diameter of 2.0mm. The obtained cylindrical strip is dried at 120℃ for 3h, and then placed in a muffle furnace at 550℃ and calcined in air atmosphere for 4h to obtain the propane dehydrogenation to propylene Pt-based molecular sieve catalyst, which is denoted as sample G.
[0078] Example 6:
[0079] A method for preparing a Pt-based molecular sieve catalyst for propane dehydrogenation to propylene includes the following steps:
[0080] (1) Weigh 162.4g TPAOH and 164.8g TEOS and dissolve them in 70.0g deionized water. Stir at room temperature for 3 hours until completely dissolved to obtain a homogeneous mixed solution.
[0081] (2) The homogeneous mixed solution from step (1) was added to a stainless steel crystallization vessel with a polytetrafluoroethylene liner and statically hydrothermally crystallized at 170°C for 48 hours. After crystallization, the mixture was naturally cooled to room temperature. The obtained product was centrifuged, the precipitate was collected and dried at 80°C for 3 hours, then ground to 200 mesh, dried at 120°C for 3 hours, and finally calcined in an air atmosphere at 550°C for 4 hours to obtain the all-silicon S-1 molecular sieve support.
[0082] (3) Weigh 0.56g H2PtCl6·6H2O and dissolve it in 2.0g deionized water. Stir at room temperature for 1h until completely dissolved to obtain a Pt-containing solution.
[0083] (4) Weigh 0.30g ZnCl2 and dissolve it in 2.0g deionized water. Stir at room temperature for 1h until completely dissolved to obtain a Zn-containing solution.
[0084] (5) Weigh 70.0g of the all-silica S-1 molecular sieve support prepared in step (2), add all of the Pt-containing solution prepared in step (3) and the Zn-containing solution prepared in step (4) into it, and soak at room temperature for 3h. Then add 27.3g of 30wt% silica sol aqueous solution, 2.0g of 65wt% concentrated nitric acid aqueous solution, 0.8g of 200-mesh unmodified wheat starch with a moisture content of 10wt% and 20.0g of deionized water. The mixture is kneaded evenly at room temperature at a speed of 20rpm in a kneader (takes 15min) until it forms an extrudable paste. Finally, it is extruded into a cylindrical strip with a diameter of 2.0mm. The obtained cylindrical strip is dried at 120℃ for 3h, and then placed in a muffle furnace at 550℃ and calcined in air atmosphere for 4h to obtain the propane dehydrogenation to propylene Pt-based molecular sieve catalyst, denoted as sample H.
[0085] Example 7:
[0086] A method for preparing a Pt-based molecular sieve catalyst for propane dehydrogenation to propylene includes the following steps:
[0087] (1) Weigh 162.4g TPAOH and 164.8g TEOS and dissolve them in 70.0g deionized water. Stir at room temperature for 3 hours until completely dissolved to obtain a homogeneous mixed solution.
[0088] (2) The homogeneous mixed solution from step (1) was added to a stainless steel crystallization vessel with a polytetrafluoroethylene liner and statically hydrothermally crystallized at 170°C for 48 hours. After crystallization, the mixture was naturally cooled to room temperature. The obtained product was centrifuged, the precipitate was collected and dried at 80°C for 3 hours, then ground to 200 mesh, dried at 120°C for 3 hours, and finally calcined in an air atmosphere at 550°C for 4 hours to obtain the all-silicon S-1 molecular sieve support.
[0089] (3) Weigh 0.56g H2PtCl6·6H2O and dissolve it in 2.0g deionized water. Stir at room temperature for 1h until completely dissolved to obtain a Pt-containing solution.
[0090] (4) Weigh 0.37 g CuCl2·2H2O and dissolve it in 2.0 g deionized water. Stir at room temperature for 1 h until completely dissolved to obtain a Cu-containing solution.
[0091] (5) Weigh 70.0g of the all-silica S-1 molecular sieve support prepared in step (2), add all of the Pt-containing solution prepared in step (3) and the Cu-containing solution prepared in step (4) into it, and soak at room temperature for 3h. Then add 27.3g of 30wt% silica sol aqueous solution, 2.0g of 65wt% concentrated nitric acid aqueous solution, 0.8g of 200-mesh unmodified wheat starch with a moisture content of 10wt% and 20.0g of deionized water. The mixture is kneaded evenly at room temperature at a speed of 20rpm in a kneader (takes 15min) until a paste-like material is formed. Finally, it is extruded into a cylindrical strip with a diameter of 2.0mm. The obtained cylindrical strip is dried at 120℃ for 3h, and then placed in a muffle furnace at 550℃ and calcined in air atmosphere for 4h to obtain the propane dehydrogenation to propylene Pt-based molecular sieve catalyst, which is denoted as sample I.
[0092] Example 8:
[0093] A method for preparing a Pt-based molecular sieve catalyst for propane dehydrogenation to propylene includes the following steps:
[0094] (1) Weigh 162.4g TPAOH and 164.8g TEOS and dissolve them in 70.0g deionized water. Stir at room temperature for 3 hours until completely dissolved to obtain a homogeneous mixed solution.
[0095] (2) The homogeneous mixed solution from step (1) was added to a stainless steel crystallization vessel with a polytetrafluoroethylene liner and statically hydrothermally crystallized at 170°C for 48 hours. After crystallization, the mixture was naturally cooled to room temperature. The obtained product was centrifuged, the precipitate was collected and dried at 80°C for 3 hours, then ground to 200 mesh, dried at 120°C for 3 hours, and finally calcined in an air atmosphere at 550°C for 4 hours to obtain the all-silicon S-1 molecular sieve support.
[0096] (3) Weigh 0.56g H2PtCl6·6H2O and dissolve it in 2.0g deionized water. Stir at room temperature for 1h until completely dissolved to obtain a Pt-containing solution.
[0097] (4) Weigh 0.38g GaCl3 and dissolve it in 2.0g deionized water. Stir at room temperature for 1h until completely dissolved to obtain a Ga-containing solution.
[0098] (5) Weigh 70.0g of the all-silica S-1 molecular sieve support prepared in step (2), add all of the Pt-containing solution prepared in step (3) and the Ga-containing solution prepared in step (4) into it, and soak at room temperature for 3h. Then add 27.3g of 30wt% silica sol aqueous solution, 2.0g of 65wt% concentrated nitric acid aqueous solution, 0.8g of 200-mesh unmodified wheat starch with a moisture content of 10wt% and 20.0g of deionized water. The mixture is kneaded evenly at room temperature at a speed of 20rpm in a kneader (takes 15min) until a paste-like material is formed. Finally, it is extruded into a cylindrical strip with a diameter of 2.0mm. The obtained cylindrical strip is dried at 120℃ for 3h, and then placed in a muffle furnace at 550℃ and calcined in air atmosphere for 4h to obtain the propane dehydrogenation to propylene Pt-based molecular sieve catalyst, which is denoted as sample J.
[0099] Table 1. Texture parameters, average mechanical strength and catalytic performance of different catalysts
[0100]
[0101] Note: The reaction conditions were as follows: catalyst loading of 0.25 g, pretreatment at 580 °C under a hydrogen atmosphere for 1 h, reaction temperature of 580 °C, reaction pressure at atmospheric pressure, reaction gas composition of 100% C3H8, and propane mass hourly space velocity (WHSV) of 8.75 h⁻¹. -1 The specific method for propane dehydrogenation to propylene is as follows: First, weigh 0.25g of catalyst and pack it into a fixed-bed reactor with an inner diameter of 12mm quartz tube, ensuring that the catalyst bed is located in the isothermal zone of the reactor heater to guarantee a uniform and stable reaction temperature. Then, introduce H2 and raise the reactor temperature to 580℃ for pretreatment for 1 hour to ensure complete catalyst activation. After pretreatment, adjust the reactor temperature to the target reaction temperature (580℃) for propane dehydrogenation to propylene, control the reaction pressure at atmospheric pressure, and finally introduce pure propane reaction gas, controlling the propane mass hourly space velocity (WHSV) to 8.75 h⁻¹. -1 The reaction of propane dehydrogenation to propylene was carried out. Product analysis was performed using gas chromatography.
[0102] Table 1 lists the texture parameters, crushing strength, and catalytic performance data of the catalysts prepared in Comparative Examples 1-2 and Examples 1-8. Comparative Example 1 did not contain a binder, Comparative Example 2 did not contain a peptide, while all examples contained binders, peptides, and other molding aids. As shown in Table 1: Regarding mechanical strength: the crushing strength of the catalysts in Examples 1-8 is significantly higher than that in Comparative Examples 1-2, indicating that the method of the present invention can effectively improve the mechanical strength of the catalyst. Regarding texture properties: the specific surface area and pore volume of the catalysts in Comparative Examples 1-2 and Examples 1-8 are not significantly different, indicating that the addition of binders, peptides, and other molding aids does not change the texture properties of the catalyst. Regarding catalytic performance: after 1 hour of reaction, the propane conversion rate of Examples 1-8 is higher than that of Comparative Examples 1-2, while the propylene selectivity is comparable to that of Comparative Examples 1-2; after 24 hours of reaction, the propane conversion rate and propylene selectivity of Examples 1-8 are significantly higher than those of Comparative Examples 1-2, indicating that the catalysts in Examples 1-8 have good catalytic performance.
[0103] Figure 1 The XRD patterns of the catalysts in Comparative Examples 1-2 and Examples 1-8 are shown. As shown in the figure, the addition of molding aids such as binders and solvents did not change the topology of the molecular sieve; the crystal phase remained intact, and the crystallinity and topology of the molecular sieve were not damaged.
[0104] Figure 2 The figures show actual molded catalysts of Comparative Examples 1-2 and Examples 1-2. As shown, the addition of molding aids such as binders and solvents significantly improved the molding performance of the catalysts, making their morphology more regular and their packing more compact, which is beneficial to improving the mechanical strength and industrial packing capacity of the catalysts.
[0105] Figure 3 The graphs show the catalytic performance evaluation of the catalysts in Comparative Examples 1-2 and Examples 1-2. (Refer to Table 1 and...) Figure 3 It is known that catalysts without binders and solvents have low mechanical strength and high particle packing. During the reaction, the catalyst particles are prone to pulverization, breakage, or wear due to the scouring of high-speed airflow, fluctuations in bed pressure, and thermal stress caused by temperature changes within the reactor. This leads to a decrease in catalyst bed porosity, an increase in pressure drop, and the potential loss of fine powder with the material, resulting in the loss of active components and ultimately a rapid decline in catalyst activity and stability. However, by introducing binders, plasticizers, solvents, and lubricants, the prepared catalyst, while maintaining the original structure and morphology of the support, not only possesses high mechanical strength but also maximizes the propane diffusion rate and the catalytic efficiency of Pt sites. This results in high activity, high propylene selectivity, and excellent resistance to carbon deposition. Furthermore, the process is simple, parameters are controllable, and it has good potential for process scale-up and industrial production.
[0106] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.
Claims
1. A method for preparing a Pt-based molecular sieve catalyst for propane dehydrogenation to propylene, characterized in that: Using molecular sieves as a carrier, active metal Pt and auxiliary metals are first introduced by impregnation, and then binders, solvents, plasticizers and lubricants are added. After being mixed evenly, the mixture is extruded and shaped, and then dried and calcined to obtain a Pt-based molecular sieve catalyst for propane dehydrogenation to propylene.
2. The preparation method according to claim 1, characterized in that: Includes the following steps: (1) Preparation of molecular sieve support The template agent and silicon source were dissolved in deionized water to obtain a homogeneous mixed solution; A homogeneous mixed solution was added to a stainless steel crystallization vessel lined with polytetrafluoroethylene and subjected to static hydrothermal crystallization. After crystallization, the solution was cooled, centrifuged, the precipitate was collected and dried, ground, dried, and calcined to obtain an all-silica molecular sieve support. The amount of feed is based on the molar amount of SiO2 contained in the silicon source, and the molar ratio of each component is: template agent: silicon source = 0.1~1.1:1, deionized water: silicon source = 3~20:1; (2) Formation of Pt-based molecular sieve catalysts Weigh out a whole silica molecular sieve support, add an active metal Pt solution and an auxiliary metal solution to it, impregnate at room temperature, then add a binder, a peptizing agent, a plasticizer and a lubricant, and knead the mixture in a kneader until it forms an extrudable paste, then extrude it into shape, and after drying and calcining, obtain a propane dehydrogenation to propylene Pt-based molecular sieve catalyst. The feed amount is based on the mass of the all-silica molecular sieve carrier, and the mass ratio of each component is as follows: active metal Pt: all-silica molecular sieve carrier = 0.003~0.009:1, auxiliary metal: all-silica molecular sieve carrier = 0.002~0.02:1, binder: all-silica molecular sieve carrier = 0~0.7:1, adhesive solvent: all-silica molecular sieve carrier = 0~0.04:1, plasticizer: all-silica molecular sieve carrier = 0.01~0.04:1, lubricant: all-silica molecular sieve carrier = 0.1~0.3:
1.
3. The preparation method according to claim 2, characterized in that: In step (1), the template agent is any one or more of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetramethylammonium bromide, and tetrabutylammonium bromide, and the silicon source is any one or more of silica sol, silica fume, and tetraethyl orthosilicate.
4. The preparation method according to claim 2, characterized in that: In step (2), the active metal component Pt solution is any one or more of PtCl2 solution, PtCl4 solution, H2PtCl6·6H2O solution, Pt(NH3)4(OH)2 solution, and Pt(NH3)4Cl2·H2O solution, and the auxiliary metal solution is any one or more of SnCl4·5H2O solution, GeCl4 solution, FeCl3·6H2O solution, MnCl2 solution, CoCl2·6H2O solution, ZnCl2 solution, CuCl2·2H2O solution, and GaCl3 solution.
5. The preparation method according to claim 2, characterized in that: In step (2), the adhesive is any one or more of silica sol, aluminum sol, and silica-alumina sol; the adhesive solvent is any one or more of concentrated sulfuric acid, concentrated nitric acid, and concentrated hydrochloric acid; the plasticizer is any one or more of wheat starch, sweet potato starch, methylcellulose, and guar gum; and the lubricant is any one or more of glycerin, vegetable oil, and deionized water.
6. The preparation method according to claim 2, characterized in that: In step (1), the crystallization temperature is 80~180℃ and the time is 8~80h; the drying temperature is 80~180℃ and the time is 2~10h; the calcination temperature is 180~800℃ and the time is 2~10h.
7. The preparation method according to claim 2, characterized in that: In step (2), the soaking time is 1~5h; the drying temperature is 80~180℃ and the time is 2~10h; the roasting temperature is 180~800℃ and the time is 2~10h.
8. A Pt-based molecular sieve catalyst for propane dehydrogenation to propylene, characterized in that: It is prepared by the preparation method according to any one of claims 1 to 7.
9. The application of the Pt-based molecular sieve catalyst for propane dehydrogenation to propylene as described in claim 8 in the catalytic reaction of propane dehydrogenation to propylene.