Rare earth single atom doped alumina supported platinum cluster catalysts, methods of making and using the same

Abstract

This invention relates to rare-earth single-atom doped alumina-supported platinum cluster catalysts, their preparation methods, and applications. The catalyst comprises a catalyst support and platinum nanoclusters dispersed on the catalyst support. The catalyst support is an alumina support doped with rare-earth elements in single-atom form. The preparation method includes the following steps: Step 1: preparing a rare-earth-aluminum composite metal oxide precursor; Step 2: preparing a catalyst support; Step 3: loading platinum onto the catalyst support; Step 4: activating the platinum-supported catalyst support. The catalyst is applied in the dehydrogenation reaction of cycloalkane. This invention, by precisely doping rare-earth elements into the alumina lattice in single-atom form, constructs stable rare-earth-oxygen active sites within the lattice, significantly promoting the migration and diffusion of hydrogen atoms from the platinum clusters to the support surface, thereby greatly enhancing the hydrogen spillover effect, improving the utilization efficiency of active hydrogen, and achieving precise control over complex reaction pathways.

Description

Technical Field

[0001] This invention relates to rare earth single-atom doped alumina supported platinum cluster catalysts, their preparation methods and applications, belonging to the technical field of catalysts for hydrocarbon hydrogenation and dehydrogenation reactions. Background Technology

[0002] Platinum-based catalysts, especially the Pt / Al2O3 system with alumina as the support, play an indispensable role in core reactions such as hydrogenation and dehydrogenation in the petrochemical industry due to their high activity and relative availability. For example, they play a core role in many industrial processes such as propane dehydrogenation to propylene and long-chain alkane hydrogenation refining. The quality of their catalytic performance is directly related to production efficiency and economic benefits.

[0003] In recent years, with the deepening of research in surface science and catalysis, the hydrogen spillover effect between metals and supports has been widely recognized as one of the key mechanisms for improving the performance of platinum-based catalysts. It plays a crucial and positive role in increasing reaction rates, optimizing reaction pathways, and even extending catalyst lifetime. Hydrogen spillover refers to the process by which active hydrogen atoms, formed by the dissociation of hydrogen molecules on platinum metal, migrate to the support surface, thereby significantly increasing the coverage and utilization efficiency of active hydrogen. This effect not only directly accelerates the kinetics of surface hydrogenation / dehydrogenation reactions but also helps to suppress carbon deposition and extend catalyst lifetime. However, the core prerequisite for achieving efficient hydrogen spillover is that the support surface must possess active sites capable of effectively binding and stabilizing hydrogen atoms. While traditional alumina supports possess ideal specific surface area and thermal stability, their surface chemistry is relatively inert, lacking specific active centers capable of strongly capturing hydrogen atoms. This makes it difficult for them to achieve effective synergy with platinum active centers, resulting in low hydrogen spillover efficiency.

[0004] Traditional Pt / Al2O3 catalysts suffer from weak synergistic effects with platinum active sites due to the chemical inertness of their alumina supports, specifically manifested in the following aspects: (1) Low hydrogen overflow efficiency: Due to the lack of efficient hydrogen atom trapping sites on the surface of alumina, the active hydrogen generated from the dissociation of platinum metal is difficult to migrate and diffuse to the surface of the support, resulting in a weak hydrogen overflow effect. A large amount of active hydrogen is bound to a limited number of platinum atoms and cannot be effectively utilized, which limits the improvement of the reaction rate. (2) Single function of active site: The reaction depends only on platinum metal site. For complex reaction networks that require the participation of support for activation (such as reactions involving hydrogenation, cracking and isomerization at the same time), traditional catalysts are difficult to control precisely, resulting in unsatisfactory selectivity of the target reaction. (3) Insufficient catalyst stability: In reactions such as high-temperature dehydrogenation, the inert regions on the surface of the support are prone to become attachment points for carbon deposit precursors. The continuous generation and coverage of carbon deposits will lead to physical blockage of the catalyst active sites, resulting in rapid catalyst deactivation and shortening its industrial service life.

[0005] The aforementioned defects make it difficult to effectively control and enhance the hydrogen spillover effect by regulating the intrinsic properties of the support, thus severely limiting further breakthroughs in the performance of traditional Pt / Al2O3 catalysts. Existing support modification methods, such as introducing metal oxide additives, often suffer from problems such as uneven distribution of additives, easy sintering or loss during the reaction, resulting in limited and unstable effects. Summary of the Invention

[0006] To overcome the aforementioned deficiencies of the prior art, this invention provides a rare-earth single-atom doped alumina-supported platinum cluster catalyst, its preparation method, and its application. This greatly enhances the hydrogen spillover effect of the catalyst and solves the technical problems of weak hydrogen spillover effect, single-function active sites, and insufficient high-temperature stability of traditional Pt / Al2O3 catalysts due to the chemical inertness of the alumina support.

[0007] The technical solution adopted in this invention is: a rare earth single-atom doped alumina supported platinum cluster catalyst, comprising a catalyst support and platinum nanoclusters dispersed on the catalyst support, wherein the catalyst support is an alumina support doped with rare earth elements in single-atom form, the rare earth elements are dispersed in the alumina lattice in single-atom form, the doping mass of the rare earth elements is 0.1% to 5% of the mass of the alumina, and the mass of the platinum nanoclusters is 0.2% to 2% of the total mass of the catalyst.

[0008] Preferably, the average particle size of the platinum nanoclusters is less than 2 nm.

[0009] Furthermore, the average particle size of the platinum nanoclusters is 1 nm to 1.5 nm.

[0010] Preferably, the rare earth element is at least one selected from cerium, lanthanum, yttrium, and erbium.

[0011] The preparation method of any of the rare earth single-atom doped alumina supported platinum cluster catalysts disclosed in this invention includes the following steps: Step 1: Preparation of rare earth-aluminum composite metal oxide precursor: The rare earth source and aluminum source are added to the liquid phase by co-precipitation to achieve atomic-level mixing. The rare earth-aluminum composite metal oxide precursor is obtained by centrifugation, washing and drying. Step 2: Preparation of catalyst support: The rare earth-aluminum composite metal oxide precursor is calcined in an oxygen-containing atmosphere at a temperature of 500℃~900℃ to obtain the catalyst support; Step 3: Loading platinum onto the catalyst support: The platinum precursor is introduced onto the catalyst support using an impregnation method; Step 4: Activation of the platinum-supported catalyst support: The platinum-supported catalyst support is dried and calcined, and then reduced in a reducing atmosphere at a temperature of 300℃~500℃ to form dispersed platinum nanoclusters on the catalyst support, thereby obtaining a rare earth single-atom doped alumina-supported platinum cluster catalyst.

[0012] Preferably, in step one, the rare earth source is a nitrate of a rare earth element, and the aluminum source is aluminum nitrate or aluminum isopropoxide.

[0013] Furthermore, the rare earth element is cerium, lanthanum, yttrium, or erbium, etc., that is, the rare earth source is cerium nitrate, lanthanum nitrate, yttrium nitrate, or erbium nitrate, etc.

[0014] Preferably, in step one, the precipitant is sodium hydroxide, sodium carbonate, ammonia, or urea.

[0015] In step one, the precipitant can be replaced by a complexing agent, which can be citric acid, ethylenediamine, or ammonium chloride.

[0016] Preferably, in step two, the oxygen-containing atmosphere is a flowing dry air atmosphere.

[0017] Preferably, in step three, the platinum precursor is chloroplatinic acid or tetraammineplatinum nitrate, etc.

[0018] Preferably, in step three, the pH value of the impregnation solution is 3 to 11.

[0019] Preferably, in step three, a complexing agent is added, such as citric acid, ammonium fluoride, or hydrochloric acid.

[0020] Preferably, in step four, the reducing atmosphere is an argon-hydrogen mixture atmosphere.

[0021] Preferably, in step four, the drying temperature is 100~200℃.

[0022] Furthermore, in step four, the drying temperature is 120°C.

[0023] Preferably, in step four, the roasting temperature is 500℃~600℃.

[0024] The application of any of the rare earth single-atom doped alumina supported platinum cluster catalysts disclosed in this invention, or rare earth single-atom doped alumina supported platinum cluster catalysts prepared by any of the preparation methods of the rare earth single-atom doped alumina supported platinum cluster catalysts disclosed in this invention, in the dehydrogenation reaction of cycloalkanes.

[0025] Preferably, the cycloalkane is methylcyclohexane or cyclohexane.

[0026] The beneficial effects of this invention are as follows: By precisely doping rare earth elements into the alumina lattice in single-atom form, this invention constructs stable rare earth-oxygen active sites within the lattice. These sites serve as efficient hydrogen traps and overflow channels, significantly promoting the migration and diffusion of hydrogen atoms from platinum clusters to the support surface, thereby greatly enhancing the hydrogen overflow effect. This not only improves the utilization efficiency of active hydrogen but also creates new active sites on the support surface that can synergistically catalyze with platinum centers, enabling precise control over complex reaction pathways. Simultaneously, the enhanced hydrogen overflow effect helps to eliminate unsaturated intermediates in the immediate process of the reaction, effectively inhibiting the formation and deposition of carbon deposits, thus significantly enhancing the catalyst's resistance to deactivation and its long-term service life under harsh reaction conditions.

[0027] This invention employs rare-earth single-atom doping technology to fundamentally alter the surface chemical properties of the alumina support, constructing an active support capable of highly efficient synergy with platinum centers. By precisely controlling the intrinsic electronic structure of the alumina support, stable, efficient, and uniformly distributed hydrogen spillover acceptor sites are created without sacrificing its structural stability. This thoroughly activates the synergistic catalytic effect between the alumina support and the platinum active center, solving key technical challenges of traditional Pt / Al2O3 catalysts, such as weak hydrogen spillover effect, single-function active sites, and insufficient high-temperature stability caused by the chemical inertness of the alumina support. This significantly improves the reaction efficiency of the catalytic reaction. Attached Figure Description

[0028] Figure 1 This is a flowchart of one embodiment of the preparation method of the rare earth single-atom doped alumina supported platinum cluster catalyst of the present invention; Figure 2 These are aberration-corrected electron microscope images of the erbium-doped alumina support prepared in Example 1 of this invention; Figure 3 This is an aberration-corrected electron microscope image of the cerium single-atom doped alumina-supported platinum cluster catalyst prepared in Example 2 of the present invention; Figure 4 These are electron microscope images of the cerium single-atom and lanthanum single-atom co-doped alumina support prepared in Example 4 of the present invention; Figure 5 This is an EDS elemental distribution diagram of cerium in the cerium single-atom and lanthanum single-atom co-doped alumina support prepared in Example 4 of the present invention; Figure 6 This is an EDS elemental distribution diagram of lanthanum in the cerium single-atom and lanthanum single-atom co-doped alumina support prepared in Example 4 of the present invention. Detailed Implementation

[0029] This invention discloses a rare-earth single-atom doped alumina-supported platinum cluster catalyst, comprising a catalyst support and platinum nanoclusters dispersed on the catalyst support. The catalyst support is an alumina support doped with rare-earth elements in single-atom form, wherein the rare-earth elements are dispersed in the alumina lattice in single-atom form, and the doping mass of the rare-earth elements is 0.1% to 5% of the mass of the alumina, for example, 0.1%, 0.5%, 1%, 3%, or 5%. The mass of the platinum nanoclusters is 0.2% to 2% (mass fraction) of the total catalyst mass, for example, 0.2%, 0.5%, 1%, 1.5%, or 2%.

[0030] The average particle size of the platinum nanoclusters is less than 2 nm, preferably 1 nm to 1.5 nm, such as 1 nm, 1.2 nm or 1.5 nm.

[0031] The rare earth element is preferably at least one of cerium, lanthanum, yttrium, and erbium, that is, the rare earth element can be one, or a combination of two or more.

[0032] See Figure 1 The present invention also discloses a method for preparing the rare earth single-atom doped alumina supported platinum cluster catalyst, comprising the following steps: Step 1: Preparation of rare earth-aluminum composite metal oxide precursor: The rare earth source and aluminum source are added to the liquid phase by co-precipitation to achieve atomic-level mixing. The rare earth-aluminum composite metal oxide precursor is obtained by centrifugation, washing and drying. Step 2: Preparation of catalyst support: The rare earth-aluminum composite metal oxide precursor is calcined in an oxygen-containing atmosphere at a temperature of 500℃~900℃ to obtain the catalyst support; Step 3: Loading platinum onto the catalyst support: The platinum precursor is introduced onto the catalyst support using an impregnation method; Step 4: Activation of the platinum-supported catalyst support: The platinum-supported catalyst support is dried and calcined, and then reduced in a reducing atmosphere at a temperature of 300℃~500℃ to form dispersed platinum nanoclusters on the catalyst support, thereby obtaining a rare earth single-atom doped alumina-supported platinum cluster catalyst.

[0033] In step one, the rare earth source can be a nitrate of a rare earth element, preferably cerium, lanthanum, yttrium, or erbium, i.e., the rare earth source is preferably cerium nitrate, lanthanum nitrate, yttrium nitrate, or erbium nitrate. The aluminum source is preferably aluminum nitrate or aluminum isopropoxide. The precipitant can be sodium hydroxide, sodium carbonate, ammonia, or urea.

[0034] In step one, the precipitant can be replaced by a complexing agent, which can be citric acid, ethylenediamine, or ammonium chloride.

[0035] In step two, the oxygen-containing atmosphere is preferably a flowing dry air atmosphere. The calcination temperature is 500℃~900℃, which is such that a stable crystal phase cannot be formed due to the temperature being too low, and rare earth elements will not precipitate or agglomerate due to the temperature being too high. The calcination time can be 3h~4h.

[0036] In step three, the platinum precursor is preferably chloroplatinic acid or tetraammineplatinum nitrate, and the pH of the impregnation solution is preferably 3-11. In step three, a complexing agent may be added, such as citric acid, ammonium fluoride, or hydrochloric acid. In step three, using the impregnation method to load platinum onto the catalyst support helps to precisely control the platinum loading.

[0037] In step four, the reducing atmosphere is preferably an argon-hydrogen mixture (10 vol.% H2 / Ar). The drying temperature can be 100~200℃, preferably 120℃. The calcination temperature is preferably 500℃~600℃. In step four, the purpose of calcination is to convert the platinum precursor into oxide, and the calcination time can be 3h~5h. The purpose of reduction is to form a platinum cluster on the catalyst support, and the reduction time can be 2h~3h.

[0038] This invention also discloses the application of any of the rare earth single-atom doped alumina supported platinum cluster catalysts disclosed herein, or rare earth single-atom doped alumina supported platinum cluster catalysts prepared by any of the preparation methods disclosed herein, in the dehydrogenation reaction of cycloalkanes.

[0039] The cycloalkane is preferably methylcyclohexane or cyclohexane.

[0040] Example 1: Step 1: Add 3.0 mmol of erbium nitrate and 47.0 mmol of aluminum isopropoxide to 100 mL of deionized water to prepare solution A with a total metal ion concentration of 0.5 mol / L. Using sodium carbonate as a precipitant, dissolve 20 g of sodium carbonate in 100 mL of deionized water to prepare solution B. Add 50 mL of deionized water to a round-bottom flask and heat to 60 °C in a water bath. While stirring, simultaneously add solutions A and B dropwise to the flask, controlling the dropping rate to maintain the pH at 10. After the addition of solutions A and B is complete, continue stirring at 60 °C for 2 hours. Centrifuge the mixed solution, wash the precipitate five times with deionized water, and dry at 120 °C to obtain the erbium-aluminum composite metal oxide precursor.

[0041] Step 2: The erbium-aluminum composite metal oxide precursor was calcined at 500℃ for 4 hours to obtain erbium single-atom doped alumina support. Aberration-corrected electron microscopy images are shown below. Figure 2 As shown.

[0042] Step 3: Add 0.061g H2PtCl6 to a mixed solution of 1.5ml deionized water and 0.5ml hydrochloric acid (concentration of 0.1mol / L) to obtain a metal salt solution with a pH of 3.0. Add the metal salt solution dropwise to the erbium single-atom doped alumina support while grinding and mixing thoroughly.

[0043] Step 4: Aging at room temperature for 12 hours, drying at 120℃, calcining at 500℃ for 5 hours, and finally reduction at 400℃ for 3 hours in an H2 / Ar atmosphere to obtain erbium single-atom doped alumina supported platinum cluster catalyst (black powder).

[0044] Example 2: Step 1: Add 4 mmol of cerium nitrate, 50 mmol of citric acid, and 46 mmol of aluminum isopropoxide to 100 mL of deionized water to prepare solution A. Using sodium hydroxide as a precipitant, dissolve 20 g of sodium hydroxide in 100 mL of deionized water to prepare solution B. Add 50 mL of deionized water to a round-bottom flask and heat to 60°C in a water bath. While stirring, simultaneously add solutions A and B dropwise to the flask, controlling the dropping rate to maintain the pH at 8. After the addition of solutions A and B is complete, continue stirring at 60°C for 2 hours. Centrifuge the mixed solution, wash the precipitate five times with deionized water, and dry at 120°C to obtain the cerium-aluminum composite metal oxide precursor.

[0045] Step 2: The cerium-aluminum composite metal oxide precursor was calcined at 600℃ for 4 hours to obtain a cerium single-atom doped alumina support.

[0046] Step 3: Add tetraammineplatinum nitrate at a loading of 0.5% to a mixed solution of 1.5 ml deionized water and 0.5 ml ammonia (concentration of 2 mol / L) to obtain a metal salt solution. The pH of the impregnation solution is 10.0. Add the metal salt solution dropwise to the cerium single-atom doped alumina support while grinding and mixing thoroughly.

[0047] Step 4: Aging at room temperature for 24 hours, drying at 120℃, calcining at 550℃ for 3 hours, and finally reduction at 500℃ for 2 hours in an H2 / Ar atmosphere to obtain a cerium single-atom doped alumina supported platinum cluster catalyst (black powder). Aberration-corrected electron microscopy image as shown below. Figure 3 As shown.

[0048] Example 3: Step 1: Prepare solution A by adding 1 mmol of lanthanum nitrate, 15 mmol of ammonium chloride, 60 mmol of aluminum isopropoxide, and 65 mmol of citric acid to 100 mL of deionized water. Prepare solution B by dissolving 20 g of sodium carbonate and 20 g of sodium hydroxide in 100 mL of deionized water using sodium carbonate and sodium hydroxide as precipitants. Add 50 mL of deionized water to a round-bottom flask and heat to 80 °C in a water bath. While stirring, add solutions A and B dropwise to the flask simultaneously, maintaining the pH at 10 by controlling the dropping rate. After the addition of solutions A and B is complete, continue stirring at 80 °C for 4 hours. Centrifuge the mixed solution, wash the precipitate five times with deionized water, and dry at 120 °C to obtain the lanthanum-aluminum composite metal oxide precursor.

[0049] Step 2: The lanthanum-aluminum composite metal oxide precursor was calcined at 600℃ for 4 hours to obtain lanthanum single-atom doped alumina support.

[0050] Step 3: Using chloroplatinic acid as a platinum precursor, measure and add it to deionized water at a loading of 1% Pt to obtain a metal salt solution with a pH of 4.0. Add the metal salt solution dropwise to the lanthanum single-atom doped alumina support while grinding and mixing thoroughly.

[0051] Step 4: Aging at room temperature for 12 hours, drying at 120℃, calcining at 550℃ for 3 hours, and finally reduction at 500℃ for 2 hours in an H2 / Ar atmosphere to obtain lanthanum single-atom doped alumina supported platinum cluster catalyst (black powder).

[0052] Example 4: Step 1: Prepare solution A by adding 5 mmol of lanthanum nitrate, 5 mmol of cerium nitrate, 70 mmol of citric acid, and 60 mmol of aluminum isopropoxide to 100 mL of deionized water. Prepare solution B by dissolving 30 mmol of saturated ammonia and 90 mmol of sodium carbonate in 100 mL of deionized water using ammonia and sodium carbonate as precipitants. Add 50 mL of deionized water to a round-bottom flask and heat to 60 °C in a water bath. While stirring, add solutions A and B dropwise to the flask simultaneously, maintaining the pH at 10 by controlling the dropping rate. After the addition of solutions A and B is complete, continue stirring at 60 °C for 2 hours. Centrifuge the mixed solution, wash the precipitate five times with deionized water, and dry at 120 °C to obtain the cerium, lanthanum-aluminum composite metal oxide precursor.

[0053] Step 2: The cerium-lanthanum-aluminum composite metal oxide precursor was calcined at 700℃ for 3 hours to obtain alumina support co-doped with cerium single atoms and lanthanum single atoms. Aberration-corrected electron microscopy images are shown below. Figure 4 As shown, the EDS elemental distribution diagram of cerium is as follows: Figure 5 As shown, the EDS elemental distribution diagram of lanthanum is as follows: Figure 6 As shown.

[0054] Step 3: Using tetraammineplatinum nitrate as the platinum precursor, weigh out the salt at a loading of 1.5% and dissolve it in a diluted ammonia solution (concentration of 1 mol / L) to obtain a metal salt solution with a pH of 11.0. Add the metal salt solution dropwise to the cerium single atom and lanthanum single atom co-doped alumina support while grinding and mixing thoroughly.

[0055] Step 4: Aging at room temperature for 12 hours, drying at 120℃, calcining at 500℃ for 3 hours, and finally reduction at 400℃ for 3 hours in an H2 / Ar atmosphere to obtain a cerium single-atom and lanthanum single-atom co-doped alumina supported platinum cluster catalyst (black powder).

[0056] Example 5: Step 1: Add 10 mmol of cerium nitrate, 20 mmol of citric acid, 20 mmol of ethylenediamine, and 80 mmol of aluminum nitrate to 100 mL of deionized water to prepare solution A. Using sodium carbonate as a precipitant, dissolve 20 g of sodium carbonate in 100 mL of deionized water to prepare solution B. Add 50 mL of deionized water to a round-bottom flask and heat to 60°C in a water bath. While stirring, simultaneously add solutions A and B dropwise to the flask, controlling the dropping rate to maintain the pH at 10. After the addition of solutions A and B is complete, continue stirring at 60°C for 2 hours. Centrifuge the mixed solution, wash the precipitate five times with deionized water, and dry at 120°C to obtain the cerium-aluminum composite metal oxide precursor.

[0057] Step 2: The cerium-aluminum composite metal oxide precursor was calcined at 700℃ for 4 hours to obtain a cerium single-atom doped alumina support.

[0058] Step 3: Using chloroplatinic acid as a platinum precursor, weigh the metal salt at a loading of 1% and add it to a dilute hydrochloric acid solution (concentration of 0.1 mol / L) to prepare a metal salt solution with a pH of 3.0. Add the metal salt solution dropwise to the cerium single-atom doped alumina support while grinding and mixing thoroughly.

[0059] Step 4: Aging at room temperature for 12 hours, drying at 120℃, calcining at 600℃ for 3 hours, and finally reduction at 400℃ for 3 hours in an H2 / Ar atmosphere to obtain cerium single-atom doped alumina supported platinum cluster catalyst (black powder).

[0060] Application Example 1: The erbium single-atom doped alumina supported platinum cluster catalyst prepared in Example 1 was used to evaluate the performance of the methylcyclohexane dehydrogenation reaction.

[0061] The evaluation device used is a dual-channel micro-reflective evaluation device from Xi'an Shiyairui Scientific Research Equipment Co., Ltd. The operating steps are as follows: 0.3 g of catalyst (erbium-doped alumina-supported platinum cluster catalyst prepared in Example 1) was weighed and thoroughly mixed with 2 g of quartz sand, and placed in a quartz reaction tube. Before the reaction began, the reaction bed temperature was raised to 300 °C, and hydrogen and nitrogen gas were introduced (gas flow rate set to 10 ml / min) to pretreat the catalyst for 0.5 h. After the pretreatment, once the reaction bed temperature stabilized at 300 °C, the introduction of hydrogen and nitrogen gas was stopped. Methylcyclohexane, the reactant, was introduced at a flow rate of 0.05 ml / min, and the reaction temperature was controlled at 300 °C. The pressure of the reaction system was atmospheric pressure. The concentrations of reactants and products were analyzed by online gas chromatography using a 0.53 × 50 mm capillary column and a flame ionization detector. Data processing was performed using a normalization method.

[0062] Evaluation results: The catalyst prepared in Example 1 achieved a methylcyclohexane (MCH) conversion of 98% and a toluene (TOL) selectivity of 99.5% at 300°C.

[0063] Application Example 2: The difference between this application example and Application Example 1 is: The catalyst was replaced with the cerium single-atom doped alumina supported platinum cluster catalyst prepared in Example 2.

[0064] Apart from the differences mentioned above, the other implementation steps and methods are the same as in Application Example 1.

[0065] Evaluation results: The catalyst prepared in Example 2 achieved a methylcyclohexane (MCH) conversion of 86% and a toluene (TOL) selectivity of 99.9% at 300°C.

[0066] Application Example 3: The difference between this application example and application example 1 is: The catalyst was replaced with the lanthanum single-atom doped alumina supported platinum cluster catalyst prepared in Example 3.

[0067] Apart from the differences mentioned above, the other implementation steps and methods are the same as in Application Example 1.

[0068] Evaluation results: The catalyst prepared in Example 3 achieved a methylcyclohexane (MCH) conversion of 94% and a toluene (TOL) selectivity of 99.8% at 300°C.

[0069] Application Example 4: The difference between this application example and application example 1 is: The catalyst was replaced with the cerium single-atom and lanthanum single-atom co-doped alumina supported platinum cluster catalyst prepared in Example 4.

[0070] Apart from the differences mentioned above, the other implementation steps and methods are the same as in Application Example 1.

[0071] Evaluation results: The catalyst prepared in Example 4 achieved a methylcyclohexane (MCH) conversion of 75% and a toluene (TOL) selectivity of 100% at 300°C.

[0072] Application Example 5: The difference between this application example and application example 1 is: The catalyst was replaced with the cerium single-atom doped alumina supported platinum cluster catalyst prepared in Example 5.

[0073] Apart from the differences mentioned above, the other implementation steps and methods are the same as in Application Example 1.

[0074] Evaluation results: The catalyst prepared in Example 5 achieved a methylcyclohexane (MCH) conversion of 99% and a toluene (TOL) selectivity of 99.8% at 300°C.

[0075] Comparative example: The difference between this comparative example and application example 1 is that: The catalyst was replaced with Pt / Al2O3 (the platinum loading was the same as that of the erbium single-atom doped alumina supported platinum cluster catalyst prepared in Example 1).

[0076] Apart from the differences mentioned above, the other implementation steps and methods are the same as in Application Example 1.

[0077] Evaluation results: The conversion rate of methylcyclohexane (MCH) using Pt / Al2O3 at 300℃ was 52%, and the selectivity for toluene (TOL) was 97.9%.

[0078] The evaluation results of each application example and comparative example are shown in Table 1.

[0079] Table 1. Comparison of Evaluation Results for Each Application Example and Comparative Example

[0080] As can be seen from the comparison results in Table 1, the rare earth single-atom doped alumina supported platinum cluster catalyst of the present invention significantly improves the methylcyclohexane conversion and toluene selectivity compared with the conventional Pt / Al2O3 catalyst for the methylcyclohexane dehydrogenation reaction.

[0081] Unless otherwise specified or further limited to one preferred or optional technical means being another, the preferred and optional technical means disclosed in this invention can be arbitrarily combined to form several different technical solutions.

[0082] Any rare-earth single-atom doped alumina supported platinum cluster catalyst or any rare-earth single-atom doped alumina supported platinum cluster catalyst preparation method of the present invention can be used in the application of any rare-earth single-atom doped alumina supported platinum cluster catalyst of the present invention in the dehydrogenation reaction of cycloalkane.

[0083] The application of any rare earth single-atom doped alumina supported platinum cluster catalyst of the present invention in the dehydrogenation reaction of cycloalkane can also be carried out by any rare earth single-atom doped alumina supported platinum cluster catalyst of the present invention or by any rare earth single-atom doped alumina supported platinum cluster catalyst preparation method.

Claims

1. A rare-earth single-atom-doped alumina-supported platinum cluster catalyst, characterized in that... The catalyst includes a catalyst support and platinum nanoclusters dispersed on the catalyst support. The catalyst support is an alumina support doped with rare earth elements in the form of single atoms. The rare earth elements are dispersed in the alumina lattice in the form of single atoms. The doping mass of the rare earth elements is 0.1% to 5% of the mass of the alumina. The mass of the platinum nanoclusters is 0.2% to 2% of the total mass of the catalyst.

2. The rare-earth single-atom doped alumina supported platinum cluster catalyst according to claim 1, characterized in that... The average particle size of the platinum nanoclusters is less than 2 nm.

3. The rare-earth single-atom doped alumina supported platinum cluster catalyst according to claim 1, characterized in that... The rare earth element is at least one of cerium, lanthanum, yttrium, and erbium.

4. The method for preparing the rare earth single-atom doped alumina supported platinum cluster catalyst according to any one of claims 1-3, characterized in that... Includes the following steps: Step 1: Preparation of rare earth-aluminum composite metal oxide precursor: The rare earth source and aluminum source are added to the liquid phase by co-precipitation to achieve atomic-level mixing. The rare earth-aluminum composite metal oxide precursor is obtained by centrifugation, washing and drying. Step 2: Preparation of catalyst support: The rare earth-aluminum composite metal oxide precursor is calcined in an oxygen-containing atmosphere at a temperature of 500℃~900℃ to obtain the catalyst support; Step 3: Loading platinum onto the catalyst support: The platinum precursor is introduced onto the catalyst support using an impregnation method; Step 4: Activation of the platinum-supported catalyst support: The platinum-supported catalyst support is dried and calcined, and then reduced in a reducing atmosphere at a temperature of 300℃~500℃ to form dispersed platinum nanoclusters on the catalyst support, thereby obtaining a rare earth single-atom doped alumina-supported platinum cluster catalyst.

5. The method for preparing the rare earth single-atom doped alumina supported platinum cluster catalyst according to claim 4, characterized in that... In step one, the rare earth source is a nitrate of a rare earth element, and the aluminum source is aluminum nitrate or aluminum isopropoxide.

6. The method for preparing the rare earth single-atom doped alumina supported platinum cluster catalyst according to claim 4, characterized in that... In step two, the oxygen-containing atmosphere is a flowing dry air atmosphere.

7. The method for preparing the rare earth single-atom doped alumina supported platinum cluster catalyst according to claim 4, characterized in that... In step three, the platinum precursor is chloroplatinic acid or tetraammineplatinum nitrate.

8. The method for preparing the rare earth single-atom doped alumina supported platinum cluster catalyst according to claim 4, characterized in that... In step three, the pH value of the impregnation solution is 3 to 11.

9. The method for preparing the rare earth single-atom doped alumina supported platinum cluster catalyst according to claim 4, characterized in that... In step four, the reducing atmosphere is a diluted hydrogen atmosphere.

10. The application of the rare earth single-atom doped alumina supported platinum cluster catalyst according to any one of claims 1-3, or the rare earth single-atom doped alumina supported platinum cluster catalyst prepared by the preparation method of any one of claims 4-9, in the dehydrogenation reaction of cycloalkane.

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