A SiO2-Al2O3 yolk-eggshell structure loaded multi-element complex phosphoric acid metal system propane dehydrogenation catalyst and a preparation method thereof

Abstract

The application belongs to the field of catalysts, and particularly relates to a SiO2-Al2O3 yolk-eggshell structure loaded multi-element complex P acid metal system propane dehydrogenation catalyst and a preparation method thereof. The catalyst is a yolk-eggshell structure, solid SiO2-Al2O3 microspheres are used as the yolk, porous SiO2-Al2O3 hollow spheres are used as the eggshell, a hydrogenation active component is loaded on the surface of the yolk, and a dehydrogenation active component is loaded on the surface of the eggshell. The dehydrogenation active component is preferably a complex system of K-Pt-Ru-Ga, phosphoric acid is used as a complexing agent to form a complex, and the complex can greatly reduce the metal agglomeration of Pt and enhance the catalytic activity.

Description

Technical Field

[0001] This invention belongs to the field of catalysts, specifically relating to a propane dehydrogenation catalyst with a SiO2-Al2O3 yolk-eggshell structure and its preparation method. Background Technology

[0002] Propylene is a fundamental chemical raw material and the source of C3 chemistry, serving as a core feedstock for PP, acrylic acid, acrylonitrile, propylene oxide, phenol, acetone, butanol, and octanol. Since 2011, light hydrocarbon cracking has become a popular choice for new projects in China, primarily due to its low investment, short construction period, streamlined process, and quick returns. Currently, two main technologies are prevalent in China: UOP's continuous catalyst regeneration technology and Lummus' fixed-bed technology. Fluidized bed technology, with a small market share, and oxidative dehydrogenation technology currently undergoing scale-up pilot testing are also available. Regarding these two mainstream processes, the Cr-based catalysts in fixed-bed processes currently lack effective recovery methods, primarily relying on landfilling, which is environmentally unfriendly. While the initial catalyst activity is high, its degradation rate is the fastest as the reaction progresses, easily forming Cr+3, which is highly toxic. Moving bed technology, a continuous catalyst regeneration technology in the UOP process, mainly uses Pt-based catalysts. Pt-based catalysts have low strength, generate significant dust, and easily clog internal and external networks, limiting the plant's operating cycle. With repeated catalyst regeneration, the catalyst activity also shows a significant downward trend.

[0003] Chinese patent CN110560038A discloses a method for preparing Cr. From a long-term environmental perspective, the inability to effectively recycle waste catalysts and their disposal through landfilling is unsustainable and may even cause secondary environmental damage. In the long run, Cr-based catalysts will inevitably be restricted in the future.

[0004] Chinese patent CN101411978A discloses a method using r-AL2O3 as a carrier. However, the carrier has low strength, the manufacturing process is lengthy, and the raw materials contain nitrogen, which makes subsequent processing inconvenient and industrialization difficult.

[0005] The propane dehydrogenation catalyst in Chinese patent CN109746027A has a relatively low catalyst support strength, which easily leads to the generation of fragments and fine powder after industrial operation. This can easily clog the internal and external meshes, affecting the operating cycle of the unit. Although its specific surface area and porosity are slightly higher than those of the UOP catalyst, the catalyst's activity and strength are not significantly altered.

[0006] Propane dehydrogenation to propylene is an endothermic process, with reaction temperatures typically ranging from 580-640℃. These high temperatures easily lead to the formation of colloids during the reaction. Fine catalyst powder and fragments mixed with these colloids can easily form lumpy blockages, which can clog the flow area. Simultaneously, high temperatures promote carbon deposition, which severely impacts catalyst activity, leading to decreased selectivity and conversion rates, and ultimately deactivation. After deactivation, the catalyst undergoes repeated carbonization, regeneration, and activation processes. The key challenge is whether the reactivated catalyst can maintain its original activity and whether its deactivation rate can remain relatively stable. Currently, improving catalyst strength and activity while reducing the deactivation rate are the focus and challenges of industrial-scale research on propane dehydrogenation catalysts. Summary of the Invention

[0007] The purpose of this invention is to solve the problems of low activity and fast deactivation rate of current propane dehydrogenation catalysts as described in the background art. Here, a propane dehydrogenation catalyst with a SiO2-Al2O3 yolk-shell structure supported on a multi-component complex metal phosphate system is proposed. This catalyst has strong catalytic activity and a low deactivation rate.

[0008] The technical solution adopted by this invention to solve its technical problem is:

[0009] A propane dehydrogenation catalyst with a SiO2-Al2O3 yolk-shell structure supporting a multi-component complexed phosphate metal system is characterized in that: the catalyst has an yolk-shell structure, with solid SiO2-Al2O3 microspheres as the yolk and porous SiO2-Al2O3 hollow spheres as the shell.

[0010] The surface of the egg yolk is loaded with a hydrogenation active component, which accounts for 0.001-0.03% of the mass of the catalyst. The hydrogenation active component is one or more of Ag, Fe, Co, Ni, Ru, Rh, Pd, Os, and Ir.

[0011] The eggshell surface is loaded with a dehydrogenation active component, which accounts for 0.15-0.65% of the mass of the catalyst. The dehydrogenation active component is one or more of K, Ru, Cr, Ni, Zn, Fe, Pt, Sn, Ca, Ga, Cu, and Al.

[0012] The diameter ratio of the egg yolk to the eggshell is 1:3-9.

[0013] As a preferred technical solution, the hydrogenation active component loaded on the egg yolk surface in the catalyst is preferably a Ni-Pd mixture, with a loading amount preferably of 0.01-0.015 wt%; the dehydrogenation active component loaded on the eggshell surface is preferably a K-Pt-Ru-Ga complex, with a loading amount preferably of 0.25-0.45 wt%.

[0014] Furthermore, the solid SiO2-Al2O3 microspheres contain 3.5-19.9 wt% SiO2, and the porous SiO2-Al2O3 hollow spheres contain 1.3-8.5 wt% SiO2.

[0015] As a preferred technical solution, the SiO2 content in the solid SiO2-Al2O3 microspheres is preferably 12.5-15.5 wt%, and the SiO2 content in the porous SiO2-Al2O3 hollow spheres is preferably 2.5-3.5 wt%.

[0016] Furthermore, the dehydrogenating active component is loaded onto the eggshell surface in the form of a complex; the complex uses the dehydrogenating active component as the forming agent and one or more of phosphate ions, organophosphate ions, halide ions, nitrate ions, and organonitrate ions as ligands. In this complex, the multi-metal formed by the dehydrogenating active component is in a positive valence state, and the ligands are in a negative valence state.

[0017] Furthermore, the complex is a multi-metal phosphate complex, the forming body is a K-Pt-Ru-Ga quaternary metal, and the ligand contains phosphate ions or organophosphate ions.

[0018] As a preferred technical solution, the complex uses a K-Pt-Ru-Ga quaternary metal as the central ion to provide a cation, a P acid as a ligand to provide an anion, and other acids as auxiliaries to provide chloride ions, thereby increasing the solubility of the metal.

[0019] Furthermore, the ligand is derived from one or more of nitric acid, hydrochloric acid, phosphoric acid, organic nitric acid, organic hydrochloric acid, tri-n-octylphosphine, ethyl phosphoric acid, tert-butylphosphine, tert-butyldichloronitric acid, or di-tert-butylphosphite.

[0020] As a preferred technical solution, the source of phosphate ions or organophosphate ions is preferably one or more of 2,2′-methylene-bis(4,6-di-tert-butylphenyl)phosphoric acid, ethylenediaminetetramethylenephosphonic acid, di(2-ethylhexyl)phosphoric acid, hydroxyethylidene diphosphonic acid, triethyl phosphate tris(1,3-dichloropropyl)phosphoric acid, or tri-n-octylphosphine, and more preferably tri-n-octylphosphine is used as the phosphorus source.

[0021] A method for preparing a propane dehydrogenation catalyst with a SiO2-Al2O3 yolk-shell structure supported on a multi-component complex metal phosphate system, comprising the following steps:

[0022] S1. Heat the aqueous solution of water-soluble aluminum salt to 45-77℃, add tetraethyl orthosilicate or organosilicon compound in several batches while stirring, add alkaline solution to adjust the pH of the solution to 7-11, filter and wash until the washing liquid is neutral to obtain filter cake, add adhesive to filter cake to make slurry, add ammonia ethanol solution to make slurry neutral, filter and dry to obtain SiO2-Al2O3 nanomaterials, add water to gelatinize, roll into shape, place in liquid nitrogen for 10-60s, rotate and atomize dry at 90℃ for 10-24h, calcine to obtain solid SiO2-Al2O3 microspheres, wherein the calcination conditions are: heating at 50℃ / h to 500-1110℃ for 3h, and the particle size of the solid SiO2-Al2O3 microspheres is 0.1-1.0mm;

[0023] S2. The solid SiO2-Al2O3 microspheres are immersed in a salt solution of hydrogenated active components for 1-5 hours and then dried to obtain solid SiO2-Al2O3 microspheres with surface-loaded hydrogenated active components.

[0024] S3. Heat the aqueous solution of water-soluble aluminum salt to 40-75℃, add tetraethyl orthosilicate or organosilicon compound in several portions while stirring, adjust the pH of the solution to 7-11 with alkali solution, filter, wash until the washing solution is neutral, dry, grind, and sieve to obtain porous SiO2-Al2O3 nanomaterials. Add template agent and binder to make a suspension slurry, then use a ball rolling method to attach the porous SiO2-Al2O3 suspension slurry to the surface of the solid SiO2-Al2O3 microspheres loaded with hydrogenated active components prepared in S2, and place them in a ball forming machine for shaping and screening. The catalyst is placed in liquid nitrogen for 10-60 seconds and then dried by rotary atomization at 90°C for 10-24 hours. Calcination yields a catalyst support with solid SiO2-Al2O3 microspheres loaded with hydrogenation active components as the yolk and porous SiO2-Al2O3 hollow spheres as the shell. The catalyst support has a size of 1.4-3.0 mm, preferably 1.8-2.8 mm. The calcination conditions are: constant temperature at 300-500°C for 1-10 hours, then heated to 500-800°C and held at 500-800°C for 1-10 hours, and finally heated to 1000°C and held at 1-2 hours, with a heating rate of 5-50°C / h.

[0025] S4. The catalyst support obtained in S3 is impregnated twice in a precursor solution of the dehydrogenation active component. The first impregnation, based on the mass of the catalyst support, involves 0.15–0.22 wt% of the loaded dehydrogenation active component for 2–6 hours. The second impregnation involves 0.15–0.35 wt% of the loaded dehydrogenation active component for 1–5 hours. Excess water is evaporated under conditions of ≤90℃ and -20–-5 kPa. The solution is washed until the pH of the washing liquid reaches 5–7. Then, it is subjected to nitrogen... A propane dehydrogenation catalyst with a SiO2-Al2O3 yolk-eggshell structure was obtained by calcination in a gas atmosphere. The calcination conditions were as follows: calcination at 260-280℃ for 10-12h, calcination at 400-430℃ for 8-10h, calcination at 530-560℃ for 8-10h, calcination at 650-700℃ for 2-4h, with a heating rate of 15-20℃ / h, and finally heating at 50℃ / h to 1000℃ and holding at that temperature for 1h.

[0026] S5. Cool the catalyst obtained in S4 to room temperature and activate it under oxychlorination conditions for 2-4 hours to obtain a chlorinated propane dehydrogenation catalyst. The chlorinated propane dehydrogenation catalyst has a chlorine content of 1.0-3.0 wt%, preferably 2.0 wt%. The chlorine content in the oxychlorination is 0.5-1 wt% of the propane dehydrogenation catalyst. The oxygen content is controlled to be 19-25 wt% of the oxychlorination gas content. The temperature is increased from room temperature to 500-550℃ at a rate ≤50℃ / h. The chlorination gas is a mixture of chlorine and oxygen.

[0027] S6. The chlorinated and activated propane dehydrogenation catalyst obtained in S5 is placed under hydrogen vapor conditions for reduction activation for 0.5-2 hours to obtain a propane dehydrogenation catalyst with reduction activity. The hydrogen vapor conditions are wherein the hydrogen content is 0.015-0.05 wt% of the propane dehydrogenation catalyst, the vapor content is 0.02-1.2 wt% of the propane dehydrogenation catalyst, the temperature is 500-620℃, and the hydrogen vapor is a mixture of hydrogen and water vapor.

[0028] In the above steps, the alkaline solution is a potassium hydroxide solution or a sodium hydroxide solution, preferably a sodium hydroxide solution.

[0029] Furthermore, the water-soluble aluminum salt is selected from one or more of anhydrous aluminum chloride, aluminum chloride hexahydrate, aluminum sulfate, aluminum nitrate, aluminum silicate, aluminum sulfide, aluminum acetate, aluminum formate, aluminum propionate, aluminum acrylate, aluminum diethyl phosphate, sodium aluminate, or potassium aluminate.

[0030] Furthermore, the adhesive is selected from one or more of acetic acid, nitric acid, hydrochloric acid, sulfuric acid, propionic acid, formic acid, fatty acids, acrylic acid, benzene hexacarboxylic acid, nitrosulfonic acid, trichloroacetic acid, trinitrobenzenesulfonic acid, trifluoromethanesulfonic acid, trifluoroacetic acid, trichloroacetic acid, 2,4,6-trinitrophenol, 2,4,6-trinitrobenzoic acid, or citric acid.

[0031] Furthermore, the template agent is selected from one or more of pyridinidine, ethylenediamine, hexamethylenediamine, tetrapropylammonium bromide, tetrapropylammonium hydroxide, n-butylamine, polyoxypropylene-polyoxyethylene, POE, PAA, or EVA.

[0032] Furthermore, the preparation method of the precursor solution of the dehydrogenation active component is as follows: ruthenium phosphate and gallium phosphate are added to a mixed solution of potassium phosphate, potassium chloride, and chloroplatinic acid under slow stirring at -10℃ to 70℃. The phosphoric acid (20-100% excess of the mixed solution volume) and hydrochloric acid (10-30% excess of the mixed solution volume) are used as a fusion solvent to regulate the phosphorus element of the non-metallic element, resulting in a KPtRuGa / PO3Cl effective metal solution, i.e., the precursor solution of the dehydrogenation active component. The precursor solution of the dehydrogenation active component is maintained at 45-65℃. The mass ratio of (potassium phosphate + potassium chloride):chloroplatinic acid:ruthenium phosphate:gallium phosphate is 1:1-0.2:1-0.05:1-0.01, preferably 1:0.2:0.08:0.03.

[0033] The catalyst preparation method of this invention employs a multi-metal complex phosphoric acid system, which effectively solves the thermodynamic equilibrium problem, creating a highly selective and high-conversion catalytic dehydrogenation system. This effectively avoids the pitot-based catalyst system. Furthermore, introducing metal elements such as Ga effectively enhances the dehydrogenation core catalyst role of Pt, avoiding metal clustering problems during catalyst regeneration, and significantly reducing the proportion of precious metals used, thus lowering catalyst costs. The use of a complex phosphoric acid system weakens acidic centers, preventing reforming reactions, reducing multi-component cyclization reactions, decreasing coking, and extending catalyst activity.

[0034] This invention utilizes an egg yolk-eggshell catalyst support structure, with solid SiO2-Al2O3 microspheres as the yolk and porous SiO2-Al2O3 hollow spheres as the shell. This prevents catalyst components from penetrating deep into the support core, thus avoiding catalyst breakage during regeneration due to the formation of core coke. It also enhances the catalyst's physical strength, preventing breakage and subsequent blockage of the internal and external meshes of the device, effectively extending the device's operating cycle and catalyst lifespan. The interaction between nano-SiO2 and the metal system prevents the clustering of nano-metal atoms, maintaining their molecular state. By controlling the content of nano-SiO2, the specific surface area can be effectively controlled, achieving a better metal weight / specific surface area ratio, thereby optimizing the metal loading ratio.

[0035] The catalyst of this invention is mainly active for dehydrogenation and auxiliary for hydrogenation. The dehydrogenation catalyst is supported on the surface and micropores of porous SiO2-Al2O3 nanospheres. The microporous structure is conducive to the uniform dispersion of noble metals and optimizes the distribution of the effective components of dehydrogenation catalysis. The active components of hydrogenation can effectively avoid the formation of coke in the center of the catalyst and simultaneously solve the catalyst breakage phenomenon in the catalyst regeneration and activation coking process.

[0036] In the preparation of the catalyst, a negative pressure rotary atomization drying method is adopted to prevent the catalyst from physically breaking down due to excessive volume expansion during the drying process.

[0037] The beneficial effects of this invention are:

[0038] 1. This invention employs a multi-metal phosphate complex system, which significantly reduces the metal aggregation of the core Pt in the existing Pt-Sn-Zn system. By using the active component of the K-Pt-Ru-Ga quaternary complex system, due to the metal interaction system of Ru and Ga, Ru and Ga will form a covalent metal system, and metal electrons will interact, reducing metal complexation, significantly reducing Pt aggregation, stimulating electron transfer between metals, and significantly increasing activity and selectivity. The method of using a complex phosphate system can weaken acidic centers, avoid the occurrence of reforming reactions, reduce multi-component cyclization reactions, reduce coking, and prolong the activity of the catalyst.

[0039] 2. This invention ensures better dispersion of the multi-metal system on the eggshell surface through two impregnations, thereby increasing the catalytic activity of the catalyst. By activating the catalyst twice and increasing chlorination activation, this step of chlorination activation can make the metal system more uniformly dispersed. At the same time, the initial catalyst introduces a higher chlorine content than conventional catalysts, which significantly reduces platinum aggregation and deactivation rate after multiple regenerations, and is more conducive to extending the activity and operating cycle of the catalyst after industrialization.

[0040] 3. The preparation method of the present invention is simple, has low energy consumption, and can reuse excess solvent components. Each step can be modularly scaled up for production, which can effectively realize industrial operation. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the catalyst structure prepared in Example 1 of the present invention;

[0042] Figure 2 This is a three-dimensional cross-sectional view of the catalyst prepared in Example 1 of the present invention;

[0043] Figure 3 This is a top view of the cross-section of the catalyst prepared in Example 1 of the present invention;

[0044] Figure 4 This is a metal distribution diagram of the catalyst EPMA prepared in Example 1 of the present invention. Detailed Implementation

[0045] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0046] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0047] The present invention will now be further illustrated with specific examples. The following embodiments are only for explaining the present invention and do not constitute a limitation thereof. The test samples and test procedures used in the following embodiments include the following (if the specific experimental conditions are not specified in the embodiments, they are usually performed according to conventional conditions or the conditions recommended by the reagent company; the reagents, consumables, etc. used in the following embodiments can be obtained commercially unless otherwise specified).

[0048] Example 1

[0049] A method for preparing a propane dehydrogenation catalyst with a SiO2-Al2O3 yolk-shell structure supporting a multi-component complex P-acid metal system, comprising the following steps:

[0050] S1. Acidic aluminum sulfate and basic potassium aluminate were mixed at a molar ratio of 7:3, and then demineralized water was added to prepare a solution. The solution was heated to 77°C, and tetraethyl orthosilicate was added in three portions with stirring. The molar ratio of tetraethyl orthosilicate to acidic aluminum sulfate was 7:3. Sodium hydroxide was then added to neutralize the pH to 11. After the reaction was completed, the solution was filtered. The resulting filter cake was washed with demineralized water until the pH of the washing solution was 7. n-Butylamine was added to the obtained filter cake to prepare a slurry. Ammonia-ethanol solution was added with stirring to make the final slurry neutral. The solution was filtered and dried to obtain SiO2-Al2O3 nanomaterials. Then, demineralized water was added to the SiO2-Al2O3 nanomaterials for gelatinization. The nanomaterials were then spheroidized into microspheres using a spheroidizing device. The microspheres were immediately transferred to liquid nitrogen for 60 seconds, and then transferred to 90°C for rotary atomization drying for 24 hours. The temperature was then increased to 1110°C at 50°C / h and calcined for 3 hours to obtain solid SiO2-Al2O3 microspheres with a particle size of 1.0 mm.

[0051] S2. The solid SiO2-Al2O3 microspheres prepared in S1 are immersed in a palladium salt solution for 5 hours and then dried in a vacuum rotary dryer to obtain solid SiO2-Al2O3 microspheres with palladium loaded on the surface.

[0052] S3. Acidic aluminum sulfate and basic potassium aluminate were mixed at a molar ratio of 7:3, and then demineralized water was added to prepare a solution. The solution was heated to 55°C, and tetraethyl orthosilicate was added with stirring, wherein the molar ratio of tetraethyl orthosilicate to acidic aluminum sulfate was 1:14. Sodium hydroxide was then added to neutralize to a pH of 9. After the reaction was complete, the solution was filtered, and the resulting filter cake was washed with demineralized water until the washing solution was neutral. The solution was dried, ground, and sieved to obtain porous SiO2-Al2O3 nanomaterials. 0.1 wt% acrylic acid and 0.1 wt% citric acid were added to the porous SiO2-Al2O3 nanomaterials to prepare a porous SiO2-Al2O3 suspension slurry. Then, a rolling ball method was used... A porous SiO2-Al2O3 suspension slurry was attached to the surface of solid SiO2-Al2O3 microspheres with palladium loaded on the surface prepared in S2. The microspheres were then shaped and screened using a spheroidizing machine, immediately transferred to liquid nitrogen for 10 seconds, and then subjected to rotary atomization drying at 90°C for 24 hours. Calcination yielded a catalyst support with palladium-loaded solid SiO2-Al2O3 microspheres as the yolk and porous SiO2-Al2O3 hollow spheres as the shell. The catalyst support had a size of 1.8 mm. The calcination conditions were: 500°C for 10 hours, then increased to 800°C for 2 hours, and finally increased to 1000°C for 1 hour, with a heating rate of 50°C / hour.

[0053] S4. The catalyst support obtained in S3 was impregnated twice in the precursor solution of the dehydrogenation active component. The first impregnation was carried out for 6 hours with a loading of 0.15 wt% K-Pt-Ru-Ga, and the second impregnation was carried out for 5 hours with a loading of 0.15 wt% K-Pt-Ru-Ga. Excess water was removed by low-temperature negative pressure steam, with the temperature controlled at ≤90℃ and the pressure at -20 kPa. After no visible water was seen, demineralized water was added to submerge the catalyst and maintain it for 45 minutes. The demineralized water washing was repeated until the pH of the demineralized water was 7. Then, calcination was started under nitrogen to obtain a propane dehydrogenation catalyst with a SiO2-Al2O3 yolk-eggshell structure. The calcination conditions were as follows: calcination at 260℃ for 10 hours, calcination at 400℃ for 8 hours, calcination at 530℃ for 8 hours, calcination at 650℃ for 2 hours, with a heating rate of 20℃ / h; finally, the temperature was raised to 1000℃ at 50℃ / h and held for 1 hour.

[0054] The preparation method for the precursor solution of the dehydrogenation active component is as follows:

[0055] Potassium phosphate, potassium chloride, chloroplatinic acid, ruthenium phosphate, and gallium phosphate were selected and mixed in a mass ratio of (potassium phosphate + potassium chloride): chloroplatinic acid: ruthenium phosphate: gallium phosphate of 1:0.2:0.05:0.01. Ruthenium phosphate and gallium phosphate were added to potassium phosphate, potassium chloride, and chloroplatinic acid under slow stirring at 20°C to form a mixed solution. The phosphorus element (P) was controlled by using a fusion solvent consisting of 20% excess phosphoric acid and 10% excess hydrochloric acid to obtain the effective metal solvent KPtRuGa / PO3Cl, which served as the precursor solution for the dehydrogenation active component, and the solution was maintained at 55°C.

[0056] S5. After cooling the propane dehydrogenation catalyst prepared in S4 to room temperature, it was transferred to oxychlorination conditions for 4 hours to activate the catalyst and obtain a chlorinated propane dehydrogenation catalyst. The specific conditions for oxychlorination were: chlorine content of 0.5 wt% of the propane dehydrogenation catalyst, oxygen content of 21 wt% of the oxychlorination gas content, and heating from room temperature to 550℃ at a rate ≤50℃ / h. The chlorine content of the chlorinated propane dehydrogenation catalyst was 1.7 wt%.

[0057] S6. The chlorinated and activated propane dehydrogenation catalyst obtained in S5 was placed under hydrogen steam conditions for reduction activation for 2 hours to obtain a propane dehydrogenation catalyst with reduction activity. The temperature was selected as 620℃, the amount of hydrogen was 0.05% of the total mass of the catalyst in excess, and the amount of steam was 0.02% of the mass of the catalyst.

[0058] The obtained propane dehydrogenation catalyst with reducing activity has a SiO2 content of 12.5% ​​in SiO2-Al2O3 microspheres and a SiO2 content of 2.5% in porous SiO2-Al2O3 hollow spheres. The active component of the hydrogenation catalyst is Pd with a loading of 0.001%, and the active component of the hydrogenation catalyst is KPtRuGa, wherein the loading of Pt is 0.20%, the loading of K is 0.96%, the loading of Ru is 0.04%, and the loading of Ga is 0.01%.

[0059] Example 2

[0060] A method for preparing a propane dehydrogenation catalyst with a SiO2-Al2O3 yolk-shell structure supporting a multi-component complex P-acid metal system, comprising the following steps:

[0061] S1. Mix acidic aluminum sulfate and basic potassium aluminate in a molar ratio of 7:3, then add demineralized water to prepare a solution. Heat to 45°C, and add tetraethyl orthosilicate in several portions while stirring. The molar ratio of tetraethyl orthosilicate to acidic aluminum sulfate is 7.5:2.5. Then add sodium hydroxide to neutralize to pH 7. After the reaction is complete, filter the solution. Wash the filter cake with demineralized water until the washing solution is neutral. Add n-butylamine to the obtained filter cake to prepare a slurry, and then add ammonia while stirring. The final slurry was neutralized by ethanol solution, filtered and dried to obtain SiO2-Al2O3 nanomaterials. Then, demineralized water was added to the SiO2-Al2O3 nanomaterials for gelatinization. Then, the nanomaterials were spheroidized into microspheres using a spheroidizing device. The microspheres were immediately transferred to liquid nitrogen for 10 seconds, and then transferred to 90°C for rotary atomization drying for 10 hours. Finally, the temperature was increased to 500°C at 50°C / h and calcined for 3 hours to obtain solid SiO2-Al2O3 microspheres with a particle size of 0.1 mm.

[0062] S2. The solid SiO2-Al2O3 microspheres prepared in S1 are immersed in the Ni salt solution of the hydrogenated active component for 1 hour, and then dried in a vacuum rotary dryer to obtain solid SiO2-Al2O3 microspheres with Ni loaded on the surface.

[0063] S3. Acidic aluminum sulfate and basic potassium aluminate were mixed at a molar ratio of 7:3, and then demineralized water was added to prepare a solution. The solution was heated to 40°C, and tetraethyl orthosilicate was added with stirring. The molar ratio of tetraethyl orthosilicate to acidic aluminum sulfate was 1:14. Sodium hydroxide was then added to neutralize the pH to 7. After the reaction was complete, the solution was filtered. The resulting filter cake was washed with demineralized water until the washing solution was neutral. The solution was dried, ground, and sieved to obtain porous SiO2-Al2O3 nanomaterials. 0.1 wt% acrylic acid and 0.1 wt% citric acid were added to the porous SiO2-Al2O3 to prepare a porous SiO2-Al2O3 suspension slurry. Then, the slurry was prepared by rolling balls. Porous SiO2-Al2O3 suspension slurry was attached to the surface of solid SiO2-Al2O3 microspheres with palladium loaded on the surface prepared in S2. The microspheres were then shaped and screened using a spheroidizing machine, immediately transferred to liquid nitrogen for 10 seconds, and then subjected to rotary atomization drying at 90°C for 10 hours. Calcination yielded a catalyst support with Ni-loaded solid SiO2-Al2O3 microspheres as the yolk and porous SiO2-Al2O3 hollow spheres as the shell. The catalyst support had a size of 1.8 mm. The calcination conditions were: constant temperature at 300°C for 1 hour, then increased to 500°C and constant temperature for 1 hour, and finally increased to 1000°C and constant temperature for 1 hour, with a heating rate of 5°C / hour.

[0064] S4. The catalyst support obtained in S3 was impregnated twice in the precursor solution of the dehydrogenation active component. The first impregnation was carried out for 6 hours with a loading of 0.22 wt% K-Pt-Ru-Ga, and the second impregnation was carried out for 5 hours with a loading of 0.35 wt% K-Pt-Ru-Ga. Excess water was removed by low-temperature negative pressure steam, with the temperature controlled at ≤90℃ and the pressure at -5 kPa. After no visible water was seen, demineralized water was added to submerge the catalyst and maintain it for 45 minutes. The demineralized water washing was repeated until the pH value of the demineralized water was 7. Then, calcination was started under nitrogen to obtain a propane dehydrogenation catalyst with a SiO2-Al2O3 yolk-eggshell structure. The calcination conditions were: calcination at 280℃ for 12 hours, calcination at 430℃ for 10 hours, calcination at 560℃ for 10 hours, calcination at 700℃ for 4 hours, with a heating rate of 20℃ / h; finally, the temperature was raised to 1000℃ at 50℃ / h and held for 1 hour.

[0065] The preparation method for the precursor solution of the dehydrogenation active component is as follows:

[0066] Potassium phosphate, potassium chloride, chloroplatinic acid, ruthenium phosphate, and gallium phosphate were selected and mixed in a mass ratio of (potassium phosphate + potassium chloride): chloroplatinic acid: ruthenium phosphate: gallium phosphate of 1:0.5:0.2:0.02. Ruthenium phosphate and gallium phosphate were added to potassium phosphate, potassium chloride, and chloroplatinic acid under slow stirring at 0°C to form a mixed solution. The phosphorus element (P) was controlled using a fusion solvent consisting of 100% excess phosphoric acid and 30% excess hydrochloric acid to obtain the effective metal solvent KPtRuGa / PO3Cl, which served as a precursor solution for the dehydrogenation active component, and the solution was maintained at 65°C.

[0067] S5. After cooling the propane dehydrogenation catalyst prepared in S4 to room temperature, it was transferred to oxychlorination conditions for 4 hours to activate the catalyst and obtain a chlorinated propane dehydrogenation catalyst. The specific conditions for oxychlorination were: chlorine content of 1% of the propane dehydrogenation catalyst, oxygen content of 25% of the oxychlorination gas content, and heating from room temperature to 550℃ with a heating rate maintained at ≤50℃. The chlorine content of the chlorinated propane dehydrogenation catalyst was 3.0 wt%.

[0068] S6. The chlorinated and activated propane dehydrogenation catalyst obtained in S5 was placed under hydrogen vapor conditions for reduction activation for 2 hours to obtain a propane dehydrogenation catalyst with reduction activity. The temperature was selected as 620℃, the amount of hydrogen was 0.05% of the total mass of the catalyst in excess, the purity of hydrogen was ≥99.9%, and the amount of vapor was 1.2% of the catalyst mass.

[0069] The obtained propane dehydrogenation catalyst with reducing activity has a SiO2 content of 5.5% in SiO2-Al2O3 microspheres and a SiO2 content of 1.5% in porous SiO2-Al2O3 hollow spheres. The active component of the hydrogenation catalyst is Ni with a loading of 0.002%, and the active component of the hydrogenation catalyst is KPtRuGa, wherein the loading of Pt is 0.18%, the loading of K is 0.32%, the loading of Ru is 0.09%, and the loading of Ga is 0.009%.

[0070] Example 3

[0071] A method for preparing a SiO2-Al2O3 egg yolk-eggshell structure supported propane dehydrogenation catalyst, the steps of which are as follows:

[0072] S1. Acidic aluminum sulfate and basic potassium aluminate are mixed at a molar ratio of 7:3, and then demineralized water is added to prepare a solution. The solution is heated to 55°C, and tetraethyl orthosilicate is added in several portions with stirring. The molar ratio of tetraethyl orthosilicate to acidic aluminum sulfate is 8:2. Sodium hydroxide is then added to neutralize the solution to pH 9. After the reaction is complete, the solution is filtered. The resulting filter cake is washed with demineralized water until the washing solution is neutral. n-Butylamine is added to the obtained filter cake to prepare a slurry, and then ammonia-ethanol solution is added with stirring to make... The final slurry reached neutrality, was filtered and dried to obtain SiO2-Al2O3 nanomaterials. Then, demineralized water was added to the SiO2-Al2O3 nanomaterials for gelatinization. The nanomaterials were then spheroidized into microspheres using a spheroidizing device and immediately transferred to liquid nitrogen for 45 seconds. After that, they were transferred to 90°C for rotary atomization drying for 18 hours. Starting from 130°C, the temperature was increased to 1000°C at a rate of 50°C / h and calcined for 3 hours to obtain solid SiO2-Al2O3 microspheres with a particle size of 0.8 mm.

[0073] S2. The solid SiO2-Al2O3 microspheres prepared in S1 are immersed in Ni-Pd metal solvent of hydrogenated active component for 4 hours, and then dried in a vacuum rotary dryer to obtain solid SiO2-Al2O3 microspheres with Ni-Pd surface loaded.

[0074] S3. Acidic aluminum sulfate and basic potassium aluminate were mixed at a molar ratio of 7:3, and then demineralized water was added to prepare a solution. The solution was heated to 55°C, and tetraethyl orthosilicate was added with stirring, wherein the molar ratio of tetraethyl orthosilicate to acidic aluminum sulfate was 1:14. Sodium hydroxide was then added to neutralize to a pH of 9. After the reaction was complete, the solution was filtered, and the resulting filter cake was washed with demineralized water until the washing solution was neutral. The solution was dried, ground, and sieved to obtain porous SiO2-Al2O3 nanomaterials. 0.1 wt% acrylic acid and 0.1 wt% citric acid were added to the porous SiO2-Al2O3 to prepare a porous SiO2-Al2O3 suspension slurry. Then, the porous SiO2-Al2O3 was slurryed using a ball rolling method. 2-Al2O3 suspension slurry was attached to the surface of solid SiO2-Al2O3 microspheres with Ni-Pd surface loading prepared in S2. The microspheres were then shaped and screened using a pelletizing machine, immediately transferred to liquid nitrogen for 40 seconds, and then subjected to rotary atomization drying at 90℃ for 16 hours. Calcination yielded a catalyst support with Ni-Pd-loaded solid SiO2-Al2O3 microspheres as the yolk and porous SiO2-Al2O3 hollow spheres as the shell. The catalyst support had a size of 2.6 mm. The calcination conditions were: 450℃ for 5 hours, then increased to 700℃ for 5 hours, and finally increased to 1000℃ for 1.5 hours, with a heating rate of 30℃ / h.

[0075] S4. The catalyst support obtained in S3 was impregnated twice in the precursor solution of the dehydrogenation active component. The first impregnation was carried out with 0.2 wt% K-Pt-Ru-Ga for 6 h, and the second impregnation was carried out with 0.15 wt% K-Pt-Ru-Ga for 3 h. Excess water was removed by low-temperature negative pressure steam, with the temperature controlled at ≤90℃ and the pressure at -20 kPa. After no visible water was seen, demineralized water was added to submerge the catalyst and maintain it for 35 min. The demineralized water washing was repeated until the pH of the demineralized water was 6. Then, calcination was started under nitrogen to obtain a propane dehydrogenation catalyst with a SiO2-Al2O3 yolk-eggshell structure. The calcination conditions were: calcination at 270℃ for 11 h, calcination at 420℃ for 9 h, calcination at 550℃ for 9 h, calcination at 680℃ for 3 h, with a heating rate of 20℃ / h; finally, the temperature was raised to 1000℃ at 50℃ / h and held for 1 h.

[0076] The preparation method for the precursor solution of the dehydrogenation active component is as follows:

[0077] Potassium phosphate, potassium chloride, chloroplatinic acid, ruthenium phosphate, and gallium phosphate were selected and mixed in a mass ratio of (potassium phosphate + potassium chloride): chloroplatinic acid: ruthenium phosphate: gallium phosphate of 1:1:0.5:0.05. Ruthenium phosphate and gallium phosphate were added to potassium phosphate, potassium chloride, and chloroplatinic acid under slow stirring at -20°C to form a mixed solution. The phosphorus element (P) was controlled using a fusion solvent consisting of 50% excess phosphoric acid and 20% excess hydrochloric acid, yielding a KPtRuGa / PO3Cl effective metal solvent. This KPtRuGa / PO3Cl solution served as a precursor solution for the dehydrogenation active component and was maintained at 55°C.

[0078] S5. After cooling the propane dehydrogenation catalyst prepared in S4 to room temperature, it was transferred to oxychlorination conditions for 3 hours to activate the catalyst and obtain a chlorinated propane dehydrogenation catalyst. The specific conditions for oxychlorination were: chlorine content of 0.6 wt% of the propane dehydrogenation catalyst, oxygen content of 21 wt% of the oxychlorination gas content, and heating from room temperature to 545℃ at a rate ≤50℃ / h. The chlorine content of the chlorinated propane dehydrogenation catalyst was 2.0 wt%.

[0079] S6. The chlorinated and activated propane dehydrogenation catalyst obtained in S5 is placed under hydrogen vapor conditions for reduction activation for 1.5 h to obtain a propane dehydrogenation catalyst with reduction activity. The temperature is selected as 550℃, the amount of hydrogen is 0.03% of the total mass of the catalyst in excess, the purity of hydrogen is ≥99.9%, and the amount of vapor is 1.0% of the mass of the catalyst.

[0080] The obtained propane dehydrogenation catalyst with reducing activity has a SiO2 content of 15% in SiO2-Al2O3 microspheres and a SiO2 content of 1.3% in porous SiO2-Al2O3 hollow spheres. The active component of the hydrogenation catalyst is Ni-Pd with a loading of 0.001%, and the active component of the hydrogenation catalyst is KPtRuGa, wherein the loading of Pt is 0.20%, the loading of K is 0.2%, the loading of Ru is 0.1%, and the loading of Ga is 0.01%.

[0081] The performance test data of existing dehydrogenation catalysts and the catalyst prepared in this invention are compared as follows:

[0082] Experimental conditions: temperature 615℃, H / HC = 0.3, H2S = 35ppm, liquid hourly space velocity 3.0, time 15min; the catalyst was analyzed by gas chromatography, and the specific results are shown in Table 1.

[0083] Table 1

[0084]

[0085] A schematic diagram of the catalyst structure prepared in Example 1 of this invention is shown below. Figure 1 See the 3D cross-sectional view. Figure 2 See the top view of the cross section. Figure 3 See EPMA metal distribution map Figure 4 , Figure 1-4 It can be seen that the catalyst prepared by the present invention has an egg yolk-eggshell structure, and the dehydrogenation active component and the hydrogenation active component are uniformly distributed on the eggshell and egg yolk surfaces, respectively.

[0086] As can be seen from Table 1, the initial strength of the catalyst of the present invention is higher than that of the existing catalysts, and the catalytic strength can be increased by more than 45%. After repeated regeneration for 100 cycles, the catalyst strength is higher than that of the existing catalysts; the single-pass conversion rate is also higher than that of the existing catalysts.

[0087] The catalysts prepared by this invention have higher initial specific surface areas than existing catalysts, and their carbon deposition rates are much lower than those of existing catalysts.

[0088] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to in the method section.

[0089] The foregoing has provided a detailed description of a SiO2-Al2O3 yolk-shell structured propane dehydrogenation catalyst and its preparation method, as provided in this invention. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above examples are merely for the purpose of helping to understand the method and core ideas of this invention. It should be noted that those skilled in the art can make various improvements and modifications to this invention without departing from its principles, and these improvements and modifications also fall within the protection scope of the claims of this invention.

Claims

1. A propane dehydrogenation catalyst supported on a SiO2-Al2O3 yolk-shell structure using a multi-component complex metal phosphate system, characterized in that: The catalyst has an egg yolk-eggshell structure, with solid SiO2-Al2O3 microspheres as the egg yolk and porous SiO2-Al2O3 hollow spheres as the eggshell. The surface of the egg yolk is loaded with a hydrogenation active component, which accounts for 0.001-0.03% of the mass of the catalyst. The hydrogenation active component is one or more of Ag, Fe, Co, Ni, Ru, Rh, Pd, Os, and Ir. The eggshell surface is loaded with a dehydrogenation active component, which accounts for 0.15-0.65% of the mass of the catalyst. The solid SiO2-Al2O3 microspheres contain 3.5-19.9 wt% SiO2, the porous SiO2-Al2O3 hollow microspheres contain 1.3-8.5 wt% SiO2, and the diameter ratio of the egg yolk to the eggshell is 1:3-9. The dehydrogenating active component is loaded on the eggshell surface in the form of a complex; the complex uses the dehydrogenating active component as the forming agent and phosphate ions or organic phosphate ions as ligands; the complex is a multi-metal phosphate complex; and the forming agent is a K-Pt-Ru-Ga quaternary metal.

2. The catalyst according to claim 1, characterized in that: The ligand is derived from one or more of phosphoric acid, tri-n-octylphosphine, ethyl phosphate, tert-butyl phosphate, or di-tert-butyl phosphite.

3. A method for preparing a propane dehydrogenation catalyst with a SiO2-Al2O3 yolk-shell structure supported on a multi-component complex metal phosphate system as described in claim 1, characterized in that: The method includes the following steps: S1. Heat the aqueous solution of water-soluble aluminum salt to 45-77℃, add tetraethyl orthosilicate or organosilicon compound in several batches while stirring, adjust the pH of the solution to 7-11 with alkali solution, filter and wash until the washing liquid is neutral to obtain filter cake, add adhesive to filter cake to make slurry, add ammonia ethanol solution to make slurry neutral, filter and dry to obtain SiO2-Al2O3 nanomaterials, gelatinize with water, roll into spheroids, place in liquid nitrogen for 10-60s, dry by rotary atomization at 90℃ for 10-24h, calcine to obtain solid SiO2-Al2O3 microspheres, wherein the calcination conditions are: heating at 50℃ / h to 500-1110℃ and calcining for 3h. S2. The solid SiO2-Al2O3 microspheres are immersed in a salt solution of hydrogenated active components for 1-5 hours and then dried to obtain solid SiO2-Al2O3 microspheres with surface-loaded hydrogenated active components. S3. Heat the aqueous solution of water-soluble aluminum salt to 40-75℃, add tetraethyl orthosilicate or organosilicon compound in several portions while stirring, adjust the pH of the solution to 7-11 with alkali solution, filter, wash until the washing solution is neutral, dry, grind, and sieve to obtain porous SiO2-Al2O3 nanomaterials. Add template agent and binder to make a suspension slurry, and then use a ball rolling method to attach the porous SiO2-Al2O3 suspension slurry to the solid SiO2-Al2O3 microspheres loaded with hydrogenated active components prepared in S2. The surface is shaped and screened in a pelletizing machine, placed in liquid nitrogen for 10-60 seconds, and dried by rotary atomization at 90℃ for 10-24 hours. Calcination yields a catalyst support with solid SiO2-Al2O3 microspheres loaded with hydrogenation active components as the yolk and porous SiO2-Al2O3 hollow spheres as the shell. The calcination conditions are: constant temperature at 300-500℃ for 1-10 hours, temperature increased to 500-800℃ and constant temperature for 1-10 hours, and finally temperature increased to 1000℃ and constant temperature for 1-2 hours, with a heating rate of 5-50℃ / h. S4. The catalyst support obtained in S3 is impregnated twice in a precursor solution of the dehydrogenation active component. The first impregnation, based on the mass of the catalyst support, involves 0.15-0.22 wt% of the loaded dehydrogenation active component for 2-6 hours. The second impregnation involves 0.15-0.35 wt% of the loaded dehydrogenation active component for 1-5 hours. Excess water is evaporated under conditions of ≤90℃ and -20~-5 kPa. The solution is washed until the pH of the washing liquid reaches 5-7. A propane dehydrogenation catalyst with a SiO2-Al2O3 yolk-eggshell structure was obtained by calcination in a gas atmosphere. The calcination conditions were as follows: calcination at 260-280℃ for 10-12h, calcination at 400-430℃ for 8-10h, calcination at 530-560℃ for 8-10h, calcination at 650-700℃ for 2-4h, with a heating rate of 15-20℃ / h, and finally heating at 50℃ / h to 1000℃ and holding at that temperature for 1h. S5. Cool the propane dehydrogenation catalyst obtained in S4 to room temperature and activate it under oxychlorination conditions for 2-4 hours to obtain a chlorinated and activated propane dehydrogenation catalyst. The chlorination activated propane dehydrogenation catalyst has a chlorine content of 1.0-3.0 wt%. The oxychlorination conditions are as follows: the chlorine content is 0.5-1 wt% of the propane dehydrogenation catalyst, the oxygen content is controlled to be 19-25 wt% of the oxychlorination gas content, and the temperature is raised from room temperature to 500-550℃ at a rate ≤50℃ / h. S6. The chlorinated and activated propane dehydrogenation catalyst obtained in S5 is placed under hydrogen vapor conditions for reduction activation for 0.5-2 hours to obtain a propane dehydrogenation catalyst with reduction activity. The hydrogen vapor conditions are wherein the hydrogen content is 0.015-0.05 wt% of the propane dehydrogenation catalyst, the vapor content is 0.02-1.2 wt% of the propane dehydrogenation catalyst, and the temperature is 500-620℃.

4. The method for preparing the propane dehydrogenation catalyst according to claim 3, characterized in that: The water-soluble aluminum salt is selected from one or more of the following: anhydrous aluminum chloride, aluminum chloride hexahydrate, aluminum sulfate, aluminum nitrate, aluminum silicate, aluminum sulfide, aluminum acetate, aluminum formate, aluminum propionate, aluminum acrylate, aluminum diethyl phosphate, sodium aluminate, or potassium aluminate.

5. The method for preparing the propane dehydrogenation catalyst according to claim 3, characterized in that: The adhesive is selected from one or more of acetic acid, nitric acid, hydrochloric acid, sulfuric acid, propionic acid, formic acid, fatty acids, acrylic acid, benzene hexacarboxylic acid, nitrosulfonic acid, trichloroacetic acid, trinitrobenzenesulfonic acid, trifluoromethanesulfonic acid, trifluoroacetic acid, trichloroacetic acid, 2,4,6-trinitrophenol, 2,4,6-trinitrobenzoic acid, or citric acid.

6. The method for preparing the propane dehydrogenation catalyst according to claim 3, characterized in that: The template agent is selected from one or more of pyridinidine, ethylenediamine, hexamethylenediamine, tetrapropylammonium bromide, tetrapropylammonium hydroxide, n-butylamine, polyoxypropylene-polyoxyethylene, POE, PAA or EVA.

7. The method for preparing the propane dehydrogenation catalyst according to claim 3, characterized in that: The preparation method of the precursor solution of the dehydrogenation active component is as follows: Ruthenium phosphate and gallium phosphate are added to potassium phosphate, potassium chloride and chloroplatinic acid at -10℃ to 70℃ to form a mixed solution. The phosphorus element of the non-metallic element is controlled by using 20-100% of the excess volume of the mixed solution of phosphoric acid and 10-30% of the excess volume of the mixed solution of hydrochloric acid as a fusion solvent to obtain KPtRuGa / PO3Cl effective metal solution, that is, the precursor solution of the dehydrogenation active component. The precursor solution of the dehydrogenation active component is maintained at 45-65℃. The mass ratio of (potassium phosphate + potassium chloride): chloroplatinic acid: ruthenium phosphate: gallium phosphate is 1:1-0.2: 1-0.05: 1-0.01.

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