Propane dehydrogenation catalyst and preparation method thereof
The catalyst of PtSn nanoparticles loaded on a rare earth-modified magnesium aluminum spinel carrier solves the problems of easy sintering and carbon deposition of Pt-based catalysts, and achieves a propane dehydrogenation reaction effect with high stability and high conversion rate.
Patent Information
- Application Number
- CN202511087068.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-05
- Publication Date
- 2025-09-23
AI Technical Summary
Existing Pt-based propane dehydrogenation catalysts are prone to sintering and carbon deposition at high temperatures, resulting in reduced catalytic activity and selectivity. The acidity of the Al2O3 support affects olefin selectivity and stability.
PtSn nanoparticles were loaded on a rare earth-modified magnesium aluminum spinel (MAS) carrier. The catalyst was prepared by hydrothermal synthesis and low-temperature reduction process. The doping of rare earth elements such as Sm, Y, Pr, La, and Ce adjusted the surface acidity and enhanced the metal-support interaction. The particle size of the nanoparticles was controlled at 1-3 nm.
The stability of the catalyst and the propane conversion rate are improved, especially when the rare earth element Sm is present, the maximum propane conversion rate and stability are exhibited, and the catalytic performance is significantly improved.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to a propane dehydrogenation catalyst and its preparation method, specifically a catalyst comprising PtSn nanoparticles supported on a rare earth-modified magnesium aluminate spinel (MAS) carrier and its preparation method. The catalyst has improved catalytic activity and stability in the propane dehydrogenation reaction. Background Art
[0002] As a key raw material for the production of high-value chemical products such as polypropylene, propylene oxide, acrolein, and acrylic acid, propylene has become an indispensable basic raw material in the chemical industry. Propane dehydrogenation to produce propylene has been widely researched and applied in industrial production. However, because propane dehydrogenation is an endothermic, thermodynamically limited reaction, high temperatures are required to achieve high propylene yields. However, these high reaction temperatures often lead to the formation of coke and light alkanes, which can lead to catalyst deactivation and reduced selectivity. This is a major challenge in the development of propane dehydrogenation catalysts.
[0003] Precious metal Pt-based catalysts are widely used in dehydrogenation reactions due to their strong C-H bond activation ability and their non-toxic and environmentally friendly properties. However, in propane dehydrogenation, Pt-based catalysts can lose catalytic activity during the reaction due to metal particle sintering and coke deposition. Therefore, improving the sintering stability and coking resistance of Pt-based catalysts is a challenge in the development of Pt-based propane dehydrogenation catalysts.
[0004] Alumina (Al2O3) is currently the most widely used catalyst support material due to its advantages, including excellent thermal stability, large specific surface area, suitable mechanical strength, high thermal conductivity, and competitive price. In the industrial propane dehydrogenation process, Al2O3 is also used as a support, supporting CrOx or PtSn active species as catalysts. Al2O3 is a typical amphoteric oxide with strong acidity, which acts as an anchor for metal species supported on its surface, significantly promoting their high dispersion, making it an excellent catalyst support material. However, the acidity of the Al2O3 support also presents certain drawbacks in alkane dehydrogenation reactions. For example, the acidic sites strongly adsorb the dehydrogenation products, stimulating further cracking reactions, resulting in reduced olefin selectivity. Furthermore, carbon deposits can form on the catalyst surface, covering the active sites and causing a rapid decrease in catalytic activity. Consequently, the reaction stability of Al2O3-supported catalysts remains unsatisfactory.
[0005] To reduce the acid strength of the Al2O3 support, alkali or alkaline earth metals, such as Ca, Mg, and K, can be added to weaken the strong acid sites on the support, thereby reducing the potential for carbon accumulation on the Al2O3 surface. Borgna et al. (Rimaz S, Chen L, Monzón A, et al. Chemical Engineering Journal, 2021, 405, 126656.) used experimental and kinetic modeling methods to investigate the effect of Ca on the catalytic performance of Pt0.5-Ge1.5 / Al2O3 in propane dehydrogenation. The addition of Ca reduced the number of acid sites on the Al2O3, increased the degree of alloying, improved propylene selectivity, and enhanced catalytic stability. Jung et al. (Lee MH, Nagaraja BM, Natarajan P, et al. Research on Chemical Intermediates, 2015, 42(1), 123-140.) prepared PtSn / Al2O3 catalysts with different K contents and investigated the effect of K on the performance of PtSn catalysts in propane dehydrogenation. The results showed that the addition of K weakened the acidity of the support and significantly inhibited the formation of cracking products at the acidic sites. Shi et al. (Shi JJ, Zhou YM, Zhang YW, et al. Journal of Materials Science, 2014, 49, 5772-5781) prepared magnesium-modified mesoporous Al2O3 as a support and loaded PtSn bimetallic species for propane dehydrogenation. In recent years, platinum-based dehydrogenation catalysts supported on magnesium aluminum spinel (MgAl2O4) have been developed. Amini et al. (Rimaz S, Sabbaghan M, Kosari M, et al. Molecular Catalysis, 2022, 531, 112695.) evaluated the catalytic performance of PtGe nanoparticles on two different supports: commercial Al2O3 and MgAl2O4 for propane dehydrogenation. The results showed that using MgAl2O4 as a support resulted in superior catalytic stability due to its anti-sintering properties and fewer acidic sites. Summary of the Invention
[0006] The present invention aims to provide a propane dehydrogenation catalyst and a preparation method thereof. The propane dehydrogenation catalyst is a catalyst comprising PtSn nanoparticles supported on a rare earth-modified magnesium aluminate spinel (MAS) carrier and a preparation method thereof.
[0007] The catalyst material, comprising platinum-tin nanoparticles supported on a rare-earth-modified magnesium-aluminum spinel, exhibits a spindle-shaped morphology. The platinum-tin metal supported on the catalyst exists as nanoparticles and is uniformly dispersed on the support surface. The particle size of the platinum-tin nanoparticles ranges from 1 to 3 nm. The catalyst, comprising PtSn nanoparticles supported on a rare-earth-modified magnesium-aluminum spinel (MAS) support, exhibits enhanced catalytic activity and stability in propane dehydrogenation reactions. In particular, when the rare-earth element doped is Sm, the catalyst exhibits the highest propane conversion and significantly improved stability, demonstrating promising application prospects.
[0008] The present invention provides a propane dehydrogenation catalyst comprising platinum-tin supported on rare-earth-modified magnesium-aluminum spinel (MAS). The catalyst material, obtained by loading platinum-tin onto rare-earth-modified magnesium-aluminum spinel, has a spindle-shaped morphology and a rich porous structure. The loaded platinum-tin metal exists in the form of nanoparticles with a particle size ranging from 1 to 3 nm and is highly dispersed on the support surface. The modified rare earth element in the catalyst is highly dispersed in the support in the form of single atoms.
[0009] The catalyst contains 0.5 wt% of platinum, 1% of tin, and 1-5% of rare earth elements, including samarium, yttrium, praseodymium, lanthanum, and cerium. Preferably, the rare earth element is samarium (Sm), with a content of 1-5 wt%.
[0010] The present invention provides a method for preparing a catalyst comprising rare earth-modified magnesium aluminum spinel carriers supporting platinum tin (PtSn) nanoparticles, comprising the following steps: 1) Dissolve aluminum nitrate, magnesium chloride, rare earth nitrate and urea in deionized water at room temperature and stir thoroughly; transfer to a reactor and conduct hydrothermal reaction at 150-200 °C for 10-12 hours; centrifuge, wash with water, dry and store in air at 1 o The temperature was raised to 500-600 °C at a heating rate of 1 / min and calcined for 1.5-2 h, followed by grinding to obtain a rare earth element modified magnesia aluminum spinel support (denoted as RE-MAS).
[0011] 2) Dissolve chloroplatinic acid hexahydrate solution and tin tetrachloride in water to obtain an impregnation solution, wherein the Pt and Sn metal ratios are 0.5 wt% and 1 wt%, respectively.
[0012] 3) Immersing the support obtained in step 1) in the impregnation solution obtained in step 2), stirring thoroughly to ensure full contact between the impregnation solution and the support, to obtain a solid product, which is then dried, calcined, and reduced to obtain a propane dehydrogenation catalyst.
[0013] The mass ratio of the synthetic raw materials in step 1) is: aluminum nitrate nonahydrate: magnesium chloride hexahydrate: samarium nitrate hexahydrate: urea: water = 201:55.4:3.6:100:350.
[0014] In step 2), the mass ratio of chloroplatinic acid hexahydrate solution to tin tetrachloride is 1:2. The proportions of Pt and Sn metals are 0.5 wt% and 1 wt%, respectively.
[0015] In the step 3), the solid product is dried in a vacuum manner at a drying temperature of 40° C. for 6 hours.
[0016] In the step 3), the calcination is carried out in an air atmosphere at a temperature of 500-600° C. for 2-3 hours.
[0017] In the step 3), the solid product is reduced at 600° C. in a hydrogen atmosphere (10% H 2 / Ar) for 2 hours.
[0018] The present invention provides a method for using the rare earth modified magnesium aluminum spinel (MAS) carrier-loaded PtSn nanoparticle catalyst in the dehydrogenation of propane to produce propylene, comprising the following steps: 1) A 40-60 mesh catalyst was weighed and loaded into a fixed-bed reactor. Before the catalytic reaction, the catalyst containing PtSn nanoparticles supported on a rare earth-modified magnesium aluminate spinel (MAS) support was first subjected to an in situ reduction treatment using 10% H2 / Ar at 600°C for 1 h.
[0019] 2) After the temperature drops to room temperature, introduce a mixture of C3H8 and N2 with a C3H8:N2 molar ratio of 1:4 and maintain a total gas flow rate of 20 mL / min.
[0020] 3) After the reaction gas was stabilized for 30 min, the temperature was raised to the target reaction temperature at a rate of 10 °C / min. The effluent gas was quantitatively analyzed using an online gas chromatograph equipped with a flame ionization detector (FID). The total reaction time was 6 h.
[0021] This invention provides a catalyst comprising PtSn nanoparticles supported on a rare earth-modified magnesium aluminate spinel (MAS) support and a preparation method thereof. The catalyst material, comprising PtSn nanoparticles supported on a rare earth-modified magnesium aluminate spinel, exhibits a spindle-shaped morphology and a rich porous structure. The PtSn metal supported on the catalyst exists as nanoparticles and is uniformly dispersed on the support surface. The PtSn nanoparticles have a particle size range of 1-3 nm, and the modified rare earth element is highly dispersed within the support as single atoms.
[0022] The catalyst of the invention, which is a rare earth-modified magnesium aluminum spinel (MAS) carrier loaded with PtSn nanoparticles, improves the catalytic activity and stability in the propane dehydrogenation reaction.
[0023] Compared with the prior art, the technical solution of the present invention has the following characteristics and the beneficial effects achieved are: First, the carrier structure has outstanding substantial characteristics. The rare earth modified magnesium aluminum spinel (RE-MAS) carrier: compared with the conventional Al2O3 carrier (strong acidity leads to carbon deposition) and the ordinary MAS carrier (such as PtGe / MgAl2O4 cited in the background technology); doping with rare earth elements (Sm / Y / Pr, etc.) can further adjust the surface acidity and enhance the metal-carrier interaction.
[0024] Secondly, the preparation process is synergistic, namely hydrothermal synthesis + low-temperature reduction process: the RE-MAS support is synthesized in a single step by hydrothermal method at 180°C (rather than traditional mechanical mixing modification), combined with vacuum drying at 40°C and H2 reduction at 600°C, which can reduce the PtSn particle size to 1–3 nm (compared to about 3–5 nm for conventional PtSn / Al2O3 particles). A rare earth-modified MAS support is prepared by a simple hydrothermal method, and then bimetallic PtSn nanoparticles are loaded by wet impregnation. Compared with ordinary Al2O3 supports, the MAS support synthesized by adding alkaline earth metal Mg has significantly reduced acidity, thereby improving the stability of the catalyst. After modifying the rare earth elements in MAS, the interaction between the Pt active metal and the rare earth-doped MAS support is further improved, giving the Pt material a strong anchoring property. After high-temperature calcination and reduction, the PtSn nanoparticles are smaller and more dispersed, thereby promoting propane conversion and stability. The results showed that, especially when the doped rare earth element was Sm, the catalyst showed the greatest propane conversion rate and stability, which were significantly improved and had good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Figure 1 Graph showing the propane conversion of the PtSn-RE-MAS catalyst of the present invention.
[0026] Figure 2 Graph showing the propane selectivity of the PtSn-RE-MAS catalyst of the present invention.
[0027] Figure 3 The catalytic performance comparison results of the PtSn-Sm-MAS catalyst prepared in the present invention (Example 1) and the comparative samples PtSn-MAS, PtSn-Sm-Al2O3 and PtSn-Al2O3 are shown.
[0028] Figure 4These are transmission electron microscope photographs and spherical aberration-corrected scanning transmission electron microscope photographs of the PtSn-Sm-MAS catalyst prepared in the present invention (Example 1), wherein the illustration in the transmission electron microscope photograph is a statistical diagram of metal particle size. DETAILED DESCRIPTION
[0029] The features of the present invention are further described below by way of examples, but the present invention is not limited to the following examples. Example
[0030] Aluminum nitrate nonahydrate, magnesium chloride hexahydrate, and samarium nitrate hexahydrate were fully dissolved in deionized water at room temperature to obtain a clear solution. After stirring for 10 minutes, urea was added to achieve a mass ratio of aluminum nitrate nonahydrate: magnesium chloride hexahydrate: samarium nitrate hexahydrate: urea: water = 201:55.4:3.5:100:350. The solution was stirred at room temperature for 30 minutes and then transferred to a Teflon-lined stainless steel reactor, sealed, and hydrothermally reacted at 180°C for 12 hours. The reaction product was centrifuged, washed with water, dried, and calcined in air at a heating rate of 1°C / min to 600°C for 2 hours to obtain the Sm-doped MAS support. According to the Pt and Sn metal proportions of 0.5 wt% and 1 wt%, respectively, hexahydrate chloroplatinic acid solution and tin tetrachloride pentahydrate were dissolved in 1 mL of deionized water and stirred until completely dissolved. The Sm-MAS support prepared above was added and stirred at room temperature for 2 h. Then, the mixture was transferred to a 40 °C vacuum oven and dried for 6 h. The obtained sample was calcined at 500 °C in an air atmosphere for 2 h and reduced at 600 °C in a hydrogen atmosphere (10% H2 / Ar) for 1 h to obtain an Sm-doped magnesium aluminum spinel-supported PtSn nanoparticle catalyst. Example
[0031] At room temperature, aluminum nitrate nonahydrate, magnesium chloride hexahydrate, and yttrium nitrate hexahydrate were fully dissolved in deionized water to obtain a clear solution. After stirring for 10 minutes, urea was added to adjust the mass ratio of the synthetic raw materials to be: aluminum nitrate nonahydrate: magnesium chloride hexahydrate: yttrium nitrate hexahydrate: urea: water = 201:55.4:3:100:350. The mixture was fully stirred at room temperature for 30 minutes, transferred to a polytetrafluoroethylene-lined stainless steel reactor, sealed, and heated at 180 o The reaction product was centrifuged, washed with water, dried, and then condensed in air at 1 oThe Y-doped MAS support was obtained by heating at a rate of 100 °C / min to 600 °C and calcining for 2 h. According to the proportion of Pt and Sn metals of 0.5 wt% and 1 wt% respectively, hexahydrate chloroplatinic acid solution and tin tetrachloride were dissolved in 1 mL of deionized water and stirred until completely dissolved. The Y-MAS support prepared above was added and stirred at room temperature for 2 h. Then, the mixture was transferred to 40 o The sample was dried in a vacuum oven at 400 °C for 6 h, calcined at 500 °C in air for 2 h, and reduced at 600 °C in a hydrogen atmosphere (10% H2 / Ar) for 1 h to obtain a Y-doped magnesium aluminum spinel-supported PtSn nanoparticle catalyst. Example
[0032] At room temperature, aluminum nitrate nonahydrate, magnesium chloride hexahydrate, and praseodymium nitrate hexahydrate were fully dissolved in deionized water to obtain a clear solution. After stirring for 10 minutes, urea was added to adjust the mass ratio of the synthetic raw materials to be: aluminum nitrate nonahydrate: magnesium chloride hexahydrate: praseodymium nitrate hexahydrate: urea: water = 201:55.4:3.5:100:350. The mixture was fully stirred at room temperature for 30 minutes, transferred to a polytetrafluoroethylene-lined stainless steel reactor, sealed, and allowed to hydrothermally react at 180°C for 12 hours. The reaction product was centrifuged, washed with water, dried, and spun in air at 1% CO. o The Pr-doped MAS support was obtained by heating the sample at a rate of 100 °C / min to 600 °C and calcining it for 2 h. A Pr-doped Mg-aluminum spinel-supported PtSn nanoparticle catalyst was obtained by dissolving chloroplatinic acid hexahydrate and tin tetrachloride in 1 mL of deionized water at a Pt and Sn metal ratio of 0.5 wt% and 1 wt%, respectively, stirring until completely dissolved. The prepared Pr-MAS support was added and stirred at room temperature for 2 h. The mixture was then transferred to a 40 °C vacuum oven and dried for 6 h. The obtained sample was calcined at 500 °C in air for 2 h and reduced at 600 °C in a hydrogen atmosphere (10% H2 / Ar) for 1 h to obtain a Pr-doped Mg-aluminum spinel-supported PtSn nanoparticle catalyst. Example
[0033] At room temperature, aluminum nitrate nonahydrate, magnesium chloride hexahydrate, and lanthanum nitrate hexahydrate were fully dissolved in deionized water to obtain a clear solution. After stirring for 10 minutes, urea was added to adjust the mass ratio of the synthetic raw materials to be: aluminum nitrate nonahydrate: magnesium chloride hexahydrate: lanthanum nitrate hexahydrate: urea: water = 201: 55.4: 3.4: 100: 350. The mixture was fully stirred at room temperature for 30 minutes, transferred to a polytetrafluoroethylene-lined stainless steel reactor, sealed, and allowed to hydrothermally react at 180°C for 12 hours. The reaction product was centrifuged, washed with water, dried, and spun in air at 1% CO. oThe La-doped MAS support was obtained by heating at a rate of 100 °C / min to 600 °C and calcining for 2 h. According to the proportion of Pt and Sn metals of 0.5 wt% and 1 wt% respectively, hexahydrate chloroplatinic acid solution and tin tetrachloride were dissolved in 1 mL of deionized water and stirred until completely dissolved. The La-MAS support prepared above was added and stirred at room temperature for 2 h. Then, the mixture was transferred to 40 o The sample was dried in a vacuum oven at 400 °C for 6 h, calcined at 500 °C in air for 2 h, and reduced at 600 °C in a hydrogen atmosphere (10% H2 / Ar) for 1 h to obtain La-doped Mg-Al spinel-supported PtSn nanoparticle catalyst. Example
[0034] At room temperature, aluminum nitrate nonahydrate, magnesium chloride hexahydrate, and cerium nitrate hexahydrate were fully dissolved in deionized water to obtain a clear solution. After stirring for 10 minutes, urea was added to adjust the mass ratio of the synthetic raw materials to be: aluminum nitrate nonahydrate: magnesium chloride hexahydrate: cerium nitrate hexahydrate: urea: water = 201: 55.4: 3.4: 100: 350. The mixture was fully stirred at room temperature for 30 minutes, transferred to a polytetrafluoroethylene-lined stainless steel reactor, sealed, and allowed to hydrothermally react at 180°C for 12 hours. The reaction product was centrifuged, washed with water, dried, and spun in air at 1% tungsten. o The temperature was raised to 600 °C at a heating rate of 100 °C / min and calcined for 2 h to obtain a Ce-doped MAS support. Chloroplatinic acid hexahydrate solution and tin tetrachloride were dissolved in 1 mL of deionized water, with the Pt and Sn metal ratios being 0.5 wt% and 1 wt%, respectively. The mixture was stirred until completely dissolved, and the Ce-MAS support prepared above was added. Stirring was continued at room temperature for 2 h, and then the mixture was transferred to a 40 °C vacuum oven and dried for 6 h. The obtained sample was calcined at 500 °C in an air atmosphere for 2 h and reduced at 600 °C in a hydrogen atmosphere (10% H2 / Ar) for 1 h to obtain a Ce-doped magnesium aluminum spinel-supported PtSn nanoparticle catalyst.
[0035] Comparative Example 1: Preparation of PtSn-MAS At room temperature, aluminum nitrate nonahydrate and magnesium chloride hexahydrate were fully dissolved in deionized water to obtain a clear solution. After stirring for 10 minutes, urea was added to adjust the mass ratio of the synthetic raw materials to be: aluminum nitrate nonahydrate: magnesium chloride hexahydrate: urea: water = 201:55.4:100:350. The mixture was fully stirred at room temperature for 30 minutes, transferred to a polytetrafluoroethylene-lined stainless steel reactor, sealed, and allowed to hydrothermally react at 180°C for 12 hours. The reaction product was centrifuged, washed with water, dried, and saturated with 1% ethanol in an air atmosphere. oThe MAS support was obtained by heating the sample at a rate of 100 °C / min to 600 °C and calcining it for 2 h. A hexahydrated chloroplatinic acid solution and tin tetrachloride were dissolved in 1 mL of deionized water, with the Pt and Sn metal ratios being 0.5 wt% and 1 wt%, respectively. The mixture was stirred until completely dissolved, and the MAS support prepared above was added. Stirring was continued at room temperature for 2 h, and then the sample was transferred to a 40 °C vacuum oven and dried for 6 h. The obtained sample was calcined at 500 °C in an air atmosphere for 2 h and reduced at 600 °C in a hydrogen atmosphere (10% H2 / Ar) for 1 h to obtain a magnesium aluminum spinel-supported PtSn nanoparticle catalyst.
[0036] Comparative Example 2: Preparation of PtSn-Sm-Al2O3 At room temperature, aluminum nitrate nonahydrate and samarium nitrate hexahydrate were fully dissolved in deionized water to obtain a clear solution. After stirring for 10 minutes, urea was added to adjust the mass ratio of the synthetic raw materials to be: aluminum nitrate nonahydrate: magnesium chloride hexahydrate: urea: water = 301:3.5:100:350. The mixture was stirred at room temperature for 30 minutes, transferred to a polytetrafluoroethylene-lined stainless steel reactor, sealed, and allowed to hydrothermally react at 180°C for 12 hours. The reaction product was centrifuged, washed with water, dried, and spun in air at 1% tungsten. o The temperature was raised to 600 °C at a heating rate of 100 °C / min and calcined for 2 h to obtain the Sm-Al2O3 support. According to the proportion of Pt and Sn metals of 0.5 wt% and 1 wt% respectively, hexahydrate chloroplatinic acid solution and tin tetrachloride were dissolved in 1 mL of deionized water and stirred until completely dissolved. The MAS support prepared above was added and stirred at room temperature for 2 h. Then, the mixture was transferred to 40 o The obtained sample was dried in a vacuum oven at 500 °C for 2 h in air atmosphere and reduced at 600 °C for 1 h in a hydrogen atmosphere (10% H2 / Ar) to obtain Sm-doped alumina-supported PtSn nanoparticle catalyst.
[0037] Comparative Example 3: Preparation of PtSn-Al2O3 At room temperature, aluminum nitrate nonahydrate was fully dissolved in deionized water to obtain a clear solution. After stirring for 10 minutes, urea was added to adjust the mass ratio of the synthetic raw materials to be: aluminum nitrate nonahydrate: magnesium chloride hexahydrate: urea: water = 301:100:350. The mixture was fully stirred at room temperature for 30 minutes, transferred to a polytetrafluoroethylene-lined stainless steel reactor, sealed, and allowed to hydrothermally react at 180°C for 12 hours. The reaction product was centrifuged, washed with water, dried, and saturated with 1% ethanol in an air atmosphere. oThe temperature was raised to 600 °C at a heating rate of 100 °C / min and calcined for 2 h to obtain an Al2O3 support. Chloroplatinic acid hexahydrate solution and tin tetrachloride were dissolved in 1 mL of deionized water, with the Pt and Sn metal ratios being 0.5 wt% and 1 wt%, respectively. The mixture was stirred until completely dissolved, and the MAS support prepared above was added. Stirring was continued at room temperature for 2 h, and then the mixture was transferred to a 40 °C vacuum oven and dried for 6 h. The obtained sample was calcined at 500 °C in an air atmosphere for 2 h and reduced at 600 °C in a hydrogen atmosphere (10% H2 / Ar) for 1 h to obtain an alumina-supported PtSn nanoparticle catalyst.
[0038] Example 6: Catalyst Performance Evaluation The conditions for catalyst evaluation are as follows: The samples obtained in Examples 1, 2, 3, 4, and 5 were used as catalysts. The catalysts were ground, tableted, and crushed, then sieved through a 40-60 mesh sieve. 100 mg of the 40-60 mesh catalyst was weighed and loaded into a fixed-bed reactor for catalytic propane dehydrogenation. Prior to the catalytic reaction, the catalysts were subjected to an in-situ reduction treatment (10% H2 / Ar, 600°C for 1 hour). After the temperature dropped to room temperature, a mixture of C3H8 and N2 (C3H8:N2 molar ratio of 1:4) was introduced at a total gas flow rate of 20 mL / min. After the reaction gas stabilized for 30 minutes, the temperature was raised to the target reaction temperature at a rate of 10°C / min. The effluent gas was quantitatively analyzed using an online gas chromatograph equipped with a flame ionization detector (FID). The reaction lasted for a total of 6 hours. The reaction results are shown in Table 1.
[0039]
[0040] From the results in Table 1, it can be seen that compared with the comparative samples PtSn-MAS, PtSn-Sm-Al2O3 and PtSn-Al2O3, the PtSn-RE-MAS catalyst prepared according to the method of the present invention exhibits excellent catalytic activity (conversion rate and propylene production rate), especially better stability and a lower deactivation rate constant during the 6-hour reaction process.
[0041] The excellent performance of the PtSn-RE-MAS catalyst is closely related to the metal structure of the catalyst. Modification of the rare earth elements in the MAS further improves the interaction between the Pt active metal and the rare earth-doped MAS support, resulting in a stronger anchoring of the Pt material. Furthermore, after high-temperature calcination and reduction, the PtSn nanoparticles are smaller and more dispersed, thereby promoting propane conversion and stability. This structural difference is the primary reason for the excellent performance of the catalyst.
Claims
1. A propane dehydrogenation catalyst, characterized in that This catalyst is made by loading platinum tin onto rare earth-modified magnesium aluminate spinel (MAS). The catalyst material is spindle-shaped and has a rich porous structure. The loaded platinum tin metal exists in the form of nanoparticles with a particle size range of 1-3 nm and is highly dispersed on the carrier surface. The loaded platinum tin metal comprises 0.5wt% platinum and 1% tin. The rare earth element is 1-5% samarium, yttrium, praseodymium, lanthanum, or cerium, or a combination thereof.
2. The propane dehydrogenation catalyst according to claim 1, characterized in that The loaded platinum-tin metal is 0.5 wt% of platinum and 1% of tin; the rare earth element is 1-5% of samarium, yttrium, praseodymium, lanthanum or cerium and a combination thereof.
3. The method for preparing the propane dehydrogenation catalyst according to claim 1, characterized in that The method for preparing the catalyst material obtained by rare earth modified magnesium aluminum spinel loaded with platinum tin comprises the following steps: 1) Dissolve aluminum nitrate, magnesium chloride, rare earth nitrate and urea in deionized water at room temperature and stir thoroughly; transfer to a reactor and conduct hydrothermal reaction at 150-200 °C for 10-12 hours; centrifuge, wash with water, dry and store in air at 1 o The temperature was raised to 500-600 °C at a heating rate of 1 / min and calcined for 1.5-2 h, followed by grinding to obtain a rare earth element-modified magnesium aluminum spinel support; 2) Dissolving chloroplatinic acid hexahydrate solution and tin tetrachloride pentahydrate in water to obtain an impregnation solution, wherein the Pt and Sn metal ratios are 0.5 wt% and 1 wt%, respectively; 3) Immersing the support obtained in step 1) in the impregnation solution obtained in step 2), stirring thoroughly to ensure full contact between the impregnation solution and the support, to obtain a solid product, which is then dried, calcined, and reduced to obtain a propane dehydrogenation catalyst.
4. The preparation method according to claim 3, characterized in that The mass ratio of the synthetic raw materials in step 1) is: aluminum nitrate nonahydrate: magnesium chloride hexahydrate: samarium nitrate hexahydrate: urea: water = 201:55.4:3.6:100:
350.
5. The preparation method according to claim 3, characterized in that The temperature of the hydrothermal reaction in step 1) is 180°C, the reaction time is 12 hours, and the calcination temperature is 600°C.
6. The preparation method according to claim 3, characterized in that The mass ratio of the chloroplatinic acid hexahydrate solution to the tin tetrachloride pentahydrate in step 2) is 1:2, and the metal contents of Pt and Sn are 0.5 wt% and 1 wt%, respectively.
7. The preparation method according to claim 3, characterized in that The solid product in step 3) is dried under vacuum at a temperature of 40° C. for 6 hours.
8. The preparation method according to claim 3, characterized in that The calcination in step 3) is carried out in an air atmosphere at a temperature of 500-600°C.
9. The preparation method according to claim 3, characterized in that The solid product in step 3) is reduced at 600° C. in a hydrogen atmosphere of 10% H 2 / Ar for 2 hours.
10. A method for using the catalyst according to claim 1 in propane dehydrogenation, characterized in that Steps involved: 1) A 40-60 mesh catalyst was weighed and loaded into a fixed-bed reactor. Before the catalytic reaction, the rare earth-modified magnesium aluminum spinel (MAS) supported PtSn nanoparticles catalyst was first subjected to in situ reduction treatment, i.e., 10% H2 / Ar, 600°C for 1 hour; 2) After the temperature drops to room temperature, introduce a mixture of C3H8 and N2 with a C3H8:N2 molar ratio of 1:4 and maintain a total gas flow rate of 20 mL / min; 3) After the reaction gas stabilized for 30 min, the temperature was raised to the target reaction temperature at a rate of 10 °C / min. The effluent gas was quantitatively analyzed using an online gas chromatograph equipped with a flame ionization detector. The total reaction time was 6 h.