A regeneration method of a supported high-entropy Pt catalyst and application thereof in preparation of propylene from propane dehydrogenation

Abstract

The application provides a regeneration method of a supported high-entropy Pt-based catalyst and application of the supported high-entropy Pt-based catalyst in preparation of propylene from propane dehydrogenation, and the regeneration method comprises the following steps: placing the supported high-entropy Pt catalyst used in the reaction of preparing propylene from propane dehydrogenation into air or oxygen-nitrogen mixed gas for calcination, and reducing the supported high-entropy Pt catalyst in a reducing atmosphere to obtain the regenerated supported high-entropy Pt catalyst. The supported high-entropy Pt catalyst comprises a carrier and a metal active component, the metal active component comprises Pt elements, Zn elements, Mn elements and A metal elements, the A metal elements are at least two of Fe, Co, Ni, Cu, Ga, Ge, In and Sn, and the mass percentage of Pt in the catalyst is 0.1-3 wt.%. After calcination, the supported high-entropy Pt catalyst used in the reaction still recovers to the initial state, and there is no sintering of Pt species. Therefore, the activity of the catalyst is still excellent and stable after multiple cyclic regeneration. The regeneration process is simple, does not pollute the environment, and compared with the industrial oxychlorination regeneration, there is no post-treatment process, and the industrial cost is saved.

Description

Technical Field

[0001] This invention relates to the field of propane dehydrogenation to propylene technology, specifically to a method for regenerating a supported high-entropy Pt-based catalyst and its application in propane dehydrogenation to propylene. Background Technology

[0002] Propylene is a key raw material for the production of various products such as polypropylene, propylene oxide, and acrylonitrile. Traditionally, propylene is produced through the thermal cracking or catalytic cracking of naphtha derived from crude oil. However, in recent years, the global shortage of oil resources has led to insufficient propylene supply. Simultaneously, with the continuous extraction of natural gas and shale gas, which contain large amounts of alkanes, the dehydrogenation of alkane to produce propylene can not only alleviate pressure on oil resources but also meet market demand. Therefore, propane dehydrogenation to propylene has attracted considerable attention among various processes.

[0003] Pt-based catalysts exhibit excellent activity in propane dehydrogenation, but high-temperature reactions lead to side reactions such as catalytic cracking and deep dehydrogenation, as well as high-temperature pyrolysis and carbon deposition at acid sites on the support. Therefore, commercial catalysts rapidly deactivate due to carbon deposition and sintering. While carbon deposits on the catalyst can be removed by combustion in an air atmosphere after the reaction, redispersing Pt is difficult. Furthermore, the exothermic combustion of carbon can cause hotspot effects or locally high temperature gradients, accelerating Pt sintering. Industrially, oxychlorination regeneration with chlorine gas is required during calcination to achieve Pt redispersibility. However, oxychlorination regeneration makes post-treatment of chlorine gas difficult, undoubtedly increasing industrial costs. To alleviate the deactivation problem during catalyst regeneration, defects are typically created on the support to enhance the interaction between the support and Pt. Alternatively, molecular sieves can be used to encapsulate and confine the active metal species. However, these methods are relatively cumbersome compared to conventional impregnation methods, and their stabilizing effect on the metal during regeneration remains limited. For example, the activity of PtSn@MFI was only one-third of its original value after the third regeneration, and the PtSn particles increased from 4 nm to 20 nm after regeneration (Nature Materials, 2019, 18, 866-873). Therefore, the stability and redispersion of Pt species during the high-temperature calcination of catalysts in air to remove carbon deposits remains a research challenge. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for regenerating a supported high-entropy Pt catalyst and its application in the dehydrogenation of propane to propylene. By simply calcining the supported high-entropy Pt catalyst to remove carbon deposits and then reducing it in a reducing atmosphere, the catalytic activity remains basically unchanged, and the catalyst is resistant to sintering during high-temperature calcination in an air atmosphere.

[0005] The regeneration method proposed in this invention targets the supported high-entropy Pt catalyst prepared in this invention.

[0006] This invention proposes a method for regenerating a supported high-entropy Pt catalyst, comprising calcining the supported high-entropy Pt catalyst after propane dehydrogenation to propylene reaction in air or an oxygen-nitrogen mixture, and then reducing it in a reducing atmosphere to obtain a regenerated supported high-entropy Pt catalyst. The supported high-entropy Pt catalyst includes a support and a metal active component, wherein the metal active component includes Pt, Zn, Mn, and Al, and the Al metal element is at least two of Fe, Co, Ni, Cu, Ga, Ge, In, and Sn; the mass percentage of Pt in the catalyst is 0.1-3 wt.%.

[0007] In the supported high-entropy Pt catalyst, the atomic percentage of Pt is 5-30%, the atomic percentage of Zn is 10-30%, the atomic percentage of Mn is 10-30%, and the atomic percentage of A is 15-65%.

[0008] The calcination temperature is 200-600℃, and the calcination time is 0.5-6h; the reduction temperature is 500-700℃, the reduction time is 0.5-4h, and the volume concentration of H2 in the reducing atmosphere is 5-100%.

[0009] The method for preparing the supported high-entropy Pt catalyst includes the following steps:

[0010] S1 mixes the metal precursor salt and the solvent to obtain a metal precursor salt solution;

[0011] S2 uses a co-impregnation or stepwise impregnation method to impregnate the metal precursor salt onto a carrier to obtain a mixture;

[0012] S3 is subjected to drying, calcination and reduction of the mixture to obtain the supported high-entropy Pt catalyst.

[0013] Optionally, the metal precursor salt is one or more of nitrates, chlorides, and acetates.

[0014] Optionally, the selected solvent may include one or more of water, methanol, and ethanol.

[0015] Optionally, the support includes one or more of nitrides, oxides, and carbides; the nitride is one or more of boron nitride and silicon nitride; the oxide is one or more of silicon oxide, aluminum oxide, and cerium oxide; and the carbide is silicon carbide.

[0016] Optionally, the carrier undergoes a drying pretreatment at a temperature of 100-180°C, preferably for a time of 1-12 hours.

[0017] Optionally, the impregnation treatment is a co-impregnation treatment.

[0018] Optionally, the concentration of the metal precursor salt solution is determined according to the metal content in the catalyst, and the volume of the precursor solution is greater than or equal to the total pore volume of the porous support. That is, the impregnation method includes equal-volume impregnation and excessive impregnation. The equal-volume impregnation is when the volume of the metal salt mixture solution is close to that of the support pores, and after impregnation, it is left to stand at room temperature to promote diffusion into the pores. The excessive impregnation is when the volume of the impregnation liquid is greater than that of the support, and stirring is required. The stirring and impregnation treatment time is 0.5-12 hours.

[0019] The concentration of the metal precursor salt solution is 0.003-0.3 mol / L.

[0020] Optionally, the drying temperature in step S3 is 40-120℃, and the drying time is 2-24h.

[0021] Optionally, the roasting atmosphere in step S3 is air, nitrogen or argon, the roasting temperature is 300-700℃, the roasting time is 2-6h, and more preferably the heating rate is 5-20℃ / min.

[0022] Optionally, in step S3, the reducing atmosphere in the reduction process is hydrogen, carbon monoxide, or nitrogen. Preferably, the reducing atmosphere is hydrogen and carbon monoxide, wherein the volume concentration of hydrogen is 5-100%; the reduction temperature is 500-700℃, the reduction time is 0.5-4h, and more preferably the heating rate is 5-20℃ / min.

[0023] The present invention also provides the application of the regeneration method in the production of propylene from propane dehydrogenation.

[0024] Optionally, the process includes passing propane or a propane-containing mixture into a fixed-bed reactor containing a supported high-entropy Pt catalyst for catalytic reaction. After the catalytic reaction, the mixture is switched to air or an oxygen-nitrogen mixture for in-situ regeneration using the regeneration method (calcination in air or an oxygen-nitrogen mixture followed by reduction in a reducing atmosphere), and then switched back to propane or a propane-containing mixture for propane dehydrogenation to propylene reaction.

[0025] The mixture also includes hydrogen and / or diluent nitrogen. When the mixture includes hydrogen, the volume ratio of propane to hydrogen is 1:0.2-1:2.

[0026] The catalytic reaction is carried out at atmospheric pressure, with a propane or propane-containing mixture flow rate of 30 ml / min and a propane concentration of 5-100% in the mixture.

[0027] The catalyst and regeneration method provided by this invention have at least the following advantages:

[0028] The catalyst, after reaction, can be calcined in air or an oxygen-nitrogen mixture and then subjected to carbon combustion, thus restoring it to its initial state without Pt species sintering. Therefore, the catalyst's activity remains excellent and stable even after multiple regeneration cycles. This regeneration process is simple, environmentally friendly, and, compared to industrial oxychlorination regeneration, eliminates the need for post-treatment processes, saving industrial costs. Attached Figure Description

[0029] Figure 1 Here is a HADDF-STEM image of the catalyst in Example A1;

[0030] Figure 2 The graph shows the regeneration cycle performance of catalyst A1 in Test Example 2 at 550℃.

[0031] Figure 3 The image shows the HADDF-STEM image of the catalyst after four regeneration cycles of catalyst A1 in Test Example 2.

[0032] Figure 4 The EXAFS spectral data of the catalyst A1 after four regeneration cycles in Test Example 2 are shown.

[0033] Figure 5 The graph shows the regeneration cycle performance of catalyst A1 in test example 3 at 500℃.

[0034] Figure 6 The graph shows the regeneration cycle performance of the C1 catalyst at 550℃ in Test Example 4. Detailed Implementation

[0035] The present invention will be further described clearly and completely below through embodiments, but is not limited to the examples described herein. The examples are only a part of the present invention, and not all of the embodiments.

[0036] Example 1

[0037] The supported high-entropy Pt-based catalyst obtained in this embodiment has a metal phase composition of Mn. 0.2 Co 0.2 Zn 0.2 Cu 0.2 Pt 0.2 The metal precursors were (CH3COO2)Mn·4H2O, Co(NO3)2·6H2O, Zn(NO3)2·6H2O, Cu(NO3)2·3H2O, and H2PtCl6. Based on the support, the mass ratio of metal Pt to support was 0.5%, and the atomic ratio of Mn, Co, Zn, Cu, and Pt was 0.2:0.2:0.2:0.2:0.2. The support used was SiO2 aerogel.

[0038] Prepare 0.3 mol / L aqueous solutions of metal salts separately. Take each metal salt solution according to the above mass ratio, dilute with deionized water to 750 μL, and ultrasonically mix thoroughly to obtain metal precursor salt solutions. Dry the silica support at 120℃ for 2 h to obtain a dried support for later use. Weigh 750 mg of the dried support into a small bottle, and use the equal-volume impregnation method to uniformly impregnate the support with the metal salt solution, and let it stand at room temperature for 2 h. Perform solvent evaporation and drying treatment on the impregnated sample at 50℃ for 12 h to obtain the first product.

[0039] The first product was calcined at 500°C for 4 hours in air at a heating rate of 5°C / min to obtain a highly dispersed high-entropy metal oxide on a silica support. Next, the supported high-entropy oxide was heated to 600°C in N2 atmosphere at a heating rate of 5°C / min, followed by treatment with 20% H2 / Ar for 2 hours to obtain a highly dispersed and stable high-entropy Pt-based catalyst, named Al. The obtained catalyst had a uniform metal particle size distribution. Figure 1 The average particle size is 1.5 nm.

[0040] Comparative Example 1

[0041] The catalyst metal phase composition obtained in this comparative example is Mn 0.4 Zn 0.4 Pt 0.2 The metal precursors were (CH3COO2)Mn·4H2O, Zn(NO3)2·6H2O, and H2PtCl6. Based on the support, the mass ratio of metal Pt to support was 0.5%, and the atomic ratio of Mn, Zn, and Pt was 0.4:0.4:0.2. The support used was SiO2 aerogel.

[0042] Prepare 0.3 mol / L aqueous solutions of metal salts separately. Take each metal salt solution according to the above mass ratio, dilute with deionized water to 600 μL, and ultrasonically mix thoroughly to obtain metal precursor salt solutions. Dry the silica support at 120℃ for 2 h to obtain a dried support for later use. Weigh 750 mg of the dried support into a small bottle, and use the equal-volume impregnation method to uniformly impregnate the support with the metal precursor salt solution, and let it stand at room temperature for 2 h. The impregnated sample is subjected to solvent evaporation and drying treatment at 50℃ for 12 h to obtain the first product.

[0043] The first product was calcined at 500°C for 4 hours in air at a heating rate of 5°C / min to obtain a metal oxide highly dispersed on a silica support. Next, the supported catalyst was heated to 600°C in N2 atmosphere at a heating rate of 5°C / min, and then treated with 20% H2 / Ar for 2 hours. The resulting catalyst was named C1.

[0044] Comparative Example 2

[0045] The catalyst metal phase composition obtained in this comparative example is Mn 0.2 Ni 0.2 Cu 0.2 :Co 0.2 Pt 0.2 The metal precursors were (CH3COO2)Mn·4H2O, Ni(NO3)2·6H2O, Cu(NO3)2·3H2O, Co(NO3)2·6H2O, and H2PtCl6. Based on the support, the mass ratio of metal Pt to support was 0.5%, and the atomic ratio of Mn, Ni, Cu, Co, and Pt was 0.2:0.2:0.2:0.2:0.2. The support used was SiO2.

[0046] Prepare 0.3 mol / L metal salt solutions separately. Take each metal salt solution according to the above mass ratio, dilute with deionized water to 600 μL, and ultrasonically mix thoroughly to obtain metal precursor salt solutions. Dry the silica support at 120℃ for 2 h to obtain a dried support for later use. Weigh 750 mg of the dried support into a small bottle, and use the equal-volume impregnation method to uniformly impregnate the support with the metal precursor salt solution, and let it stand at room temperature for 2 h. The impregnated sample is subjected to solvent evaporation and drying treatment at 50℃ for 12 h to obtain the first product.

[0047] The first product was calcined at 500°C for 4 hours in air at a heating rate of 5°C / min to obtain a metal oxide highly dispersed on a silica support. Next, the supported oxide was heated to 600°C in N2 atmosphere at a heating rate of 5°C / min, and then treated with 20% H2 / Ar for 2 hours. The resulting catalyst was named C2.

[0048] Comparative Example 3

[0049] The catalyst PtSn / Al2O3 obtained in this comparative example had SnCl2·2H2O and H2PtCl6 as metal precursors. Based on the support, the mass ratio of metal Pt to support was 0.5%, and the Sn loading was 1 wt.%. The support used was commercial Al2O3.

[0050] Prepare 0.3 mol / L metal salt solutions separately, dilute with deionized water to 600 μL according to the above-mentioned mass, and ultrasonically mix thoroughly to obtain metal precursor salt solutions. Dry the alumina support at 120℃ for 2 h to obtain a dried support for later use. Weigh 750 mg of the dried support into a small bottle, and uniformly impregnate the support with the metal precursor salt solution using an equal-volume impregnation method, and let it stand at room temperature for 2 h. Perform solvent evaporation and drying treatment on the impregnated sample at 50℃ for 12 h to obtain the first product. Calcinate the first product in air at a heating rate of 5℃ / min at 500℃ for 4 h to obtain the PtSn / Al2O3 catalyst, named C3.

[0051] The specific calculation methods for the Pt loading and the content of each metal in the catalyst obtained in the above embodiments and comparative examples are as follows: The loading is a theoretically calculated value. According to the target loading, the solutions of each metal precursor are measured. The Pt loading is the mass ratio of Pt to SiO2 or Al2O3. Based on this, the amount of each metal element added is determined according to the molar ratio of Pt to each metal element. Some parameters of each embodiment and comparative example are shown in Table 1.

[0052] Table 1. Parameters for each embodiment and comparative example.

[0053] 1 A1 1 / 200 Mn:Co:Zn:Cu:Pt=0.2:0.2:0.2:0.2:0.2 <![CDATA[SiO2]]> Comparative Example Catalyst name Pt to carrier mass ratio Molar ratio of each metal carrier 1 C1 1 / 200 Mn:Zn:Pt = 0.4:0.4:0.2 <![CDATA[SiO2]]> 2 C2 1 / 200 Mn:Ni:Cu:Co:Pt=0.2:0.2:0.2:0.2:0.2 <![CDATA[SiO2]]> 3 C3 1 / 200 Pt:Sn = 1:2.6 <![CDATA[Al2O3]]>

[0054] The following test examples 1-5 illustrate the propane dehydrogenation to propylene production using the catalysts from the above examples and comparative examples.

[0055] The reaction test uses a fixed-bed reactor, equipped with an open-tube resistance furnace and an intelligent temperature controller to provide heat for the reaction and to detect and control the temperature; a seven-star flow meter controller controls the flow rate.

[0056] The alkane and olefin contents in the product were analyzed online using a GC7900 gas chromatograph, and the reaction conversion rate and product selectivity were calculated. The product selectivity was calculated using the area normalization method.

[0057] Test Example 1

[0058] The propane dehydrogenation and regeneration cycle performance of the A1 catalyst obtained in Example 1 was determined in a continuous fixed-bed microreactor. Specific conditions were as follows: catalyst dosage 0.1 g, reaction temperature 600 °C, reaction pressure atmospheric pressure, and total flow rate of the reaction gas (mixed gas) 30 ml / min, of which propane flow rate was 3 ml / min, H2 flow rate was 3 ml / min, and the remainder was N2 flow rate. The specific regeneration cycle process was as follows: After the catalyst A1 reacted for 8 hours, the reaction gas was shut off, and the temperature was lowered to 500 °C under a nitrogen atmosphere. Then, a 20% O2 / N2 mixed gas was introduced for calcination for 30 minutes to remove carbon deposits on the catalyst. After calcination, the temperature was further increased to 600 °C under a nitrogen atmosphere, and 20% H2 / Ar was introduced for in-situ treatment for 2 hours. Then, the reaction gas was introduced again to carry out the propane dehydrogenation to propylene reaction. The above reaction, calcination, and reduction processes were then repeated. In the initial test, the A1 catalyst showed an initial propane conversion of 56.7% and a propylene selectivity of 94.2%. After 480 min of reaction, the propane conversion was 53.4%, and the propylene selectivity stabilized at 94.6%. After the second regeneration, the initial propane conversion was 54.9%, and the propylene selectivity was 94.3%. After 480 min of reaction, the propane conversion was 51.6%, the propylene selectivity was 94.9%, and the deactivation rate constant was 0.016 h⁻¹. -1 .

[0059] Test Example 2

[0060] The propane dehydrogenation and regeneration cycle performance of the A1 catalyst obtained in Example 1 was determined in a continuous fixed-bed microreactor. Specific conditions were as follows: catalyst dosage 0.1 g, reaction temperature 550 °C, reaction pressure atmospheric pressure, total reaction gas flow rate 30 ml / min, of which propane flow rate was 3 ml / min, H2 flow rate was 3 ml / min, and the remainder was N2 flow rate. The specific regeneration cycle process was as follows: the calcined catalyst was treated in situ at 600 °C with 20% H2 / Ar for 2 h, followed by cooling to 500 °C for further reaction. After 8 hours of reaction, the reaction gas of the A1 catalyst was shut off, and the temperature was lowered to 500°C under a nitrogen atmosphere. Then, a 20% O2 / N2 mixture was introduced for calcination for 30 minutes to remove carbon deposits on the catalyst. After calcination, the temperature was raised to 600°C under a nitrogen atmosphere, and then treated in situ with 20% H2 / Ar for 2 hours. The temperature was then lowered to 550°C under a nitrogen atmosphere, and the reaction gas was introduced again to carry out the propane dehydrogenation to propylene reaction. The above reaction, calcination, and reduction process was then repeated. The catalyst was recycled four times. The initial propane conversion rate of the A1 catalyst in the initial test was 37.4%, and the propylene selectivity was 97%. After four cycles of air calcination at 500°C and reduction regeneration, the propane conversion rate remained above 34.4%, and the propylene selectivity stabilized at 93.6% (e.g., ...). Figure 2 ).

[0061] The sample obtained after the fourth regeneration cycle in Test Example 2 was analyzed using a high-angle annular dark-field scanning electron microscope (HAADF-STEM). The results are as follows: Figure 3 As shown, the catalyst particles remain uniformly distributed, with no large particle aggregation. A particle size distribution diagram obtained through particle size analysis shows that the catalyst particles are mainly concentrated around 2.0 nm (e.g., ...). Figure 3 ).

[0062] Extended edge X-ray absorption fine structure (EXAFS) spectroscopy further analyzed the coordination structure of platinum after the fourth regeneration cycle in Test Example 2. Figure 4 Comparison with Pt foil revealed no peaks in platinum-platinum bonds in this sample, indicating that platinum atoms did not undergo significant sintering.

[0063] Test Example 3

[0064] The propane dehydrogenation and regeneration cycle performance of the A1 catalyst obtained in Example 1 was determined in a continuous fixed-bed microreactor. Specific conditions were as follows: catalyst dosage 0.1 g, reaction temperature 500 °C, reaction pressure atmospheric pressure, and total reaction gas flow rate 30 ml / min, of which propane flow rate was 3 ml / min, H2 flow rate was 3 ml / min, and the remainder was N2 flow rate. The specific regeneration cycle process was as follows: After the catalyst A1 reacted for 8 hours, the reaction gas was shut off, and the temperature was lowered to 500 °C under a nitrogen atmosphere. Then, a 20% O2 / N2 mixture was introduced for calcination for 30 minutes to remove carbon deposits on the catalyst. After calcination, the temperature was further increased to 600 °C under a nitrogen atmosphere, and 20% H2 / Ar was introduced for in-situ treatment for 2 hours. The temperature was then lowered to 500 °C under a nitrogen atmosphere, and the reaction gas was introduced again to carry out the propane dehydrogenation to propylene reaction. The above reaction, calcination, and reduction process was then repeated. The catalyst was recycled four times. The initial propane conversion of the A1 catalyst was 18% and the propylene selectivity was 93.8% during the initial test. After four cycles of air roasting and regeneration at 500℃, the propane conversion remained above 17.2%, and the propylene selectivity remained stable at 93%. Figure 5 ).

[0065] Test Example 4

[0066] The propane dehydrogenation and regeneration cycle performance of the C1 catalyst obtained in Example 2 was determined in a continuous fixed-bed microreactor. Specific conditions were as follows: catalyst dosage 0.1 g, reaction temperature 550 °C, reaction pressure atmospheric pressure, and total reaction gas flow rate 30 ml / min, of which propane flow rate was 3 ml / min, H2 flow rate was 3 ml / min, and the remainder was N2 flow rate. The specific regeneration process was as follows: After the C1 catalyst reacted for 8 hours, the reaction gas was shut off, and the temperature was lowered to 500 °C under a nitrogen atmosphere. Then, a 20% O2 / N2 mixture was introduced for calcination for 30 minutes to remove carbon deposits on the catalyst. After calcination, the temperature was further increased to 600 °C under a nitrogen atmosphere, and then treated in situ with 20% H2 / Ar for 2 hours. The temperature was then lowered to 550 °C under a nitrogen atmosphere for further reaction. The above reaction, calcination, and reduction processes were then repeated. The catalyst was recycled four times. The initial propane conversion rate of the catalyst was 33% and the propylene selectivity was 98.5% during the initial test. After four cycles of air roasting and regeneration at 500°C, the propylene selectivity remained at 98%, but the propane conversion rate was only 21% (e.g., ...). Figure 6 The catalyst is rapidly deactivated after regeneration.

[0067] Test Example 5

[0068] The propane dehydrogenation performance of the C2 catalyst obtained in Comparative Example 2 was determined in a continuous fixed-bed microreactor. Specific conditions were as follows: catalyst dosage 0.1 g, reaction temperature 600 °C, reaction pressure atmospheric pressure, total reaction gas flow rate 30 mL / min (propane 3 mL / min, H2 3 mL / min, nitrogen 24 mL / min). The initial propane conversion was 63%, and the propylene selectivity was 74%. After 8 h of reaction, the propane conversion was only 43%, the propylene selectivity was 91%, and the catalyst deactivation rate was 0.102 h. -1 This catalyst, lacking Zn species, undergoes significant deactivation during propane dehydrogenation.

[0069] Test Example 6

[0070] The propane dehydrogenation and regeneration cycle performance of the C3 catalyst obtained in Comparative Example 3 was determined in a continuous fixed-bed microreactor. Specific conditions were as follows: catalyst dosage 0.1 g, reaction temperature 550 °C, reaction pressure atmospheric pressure, and total reaction gas flow rate 30 ml / min, of which propane flow rate was 3 ml / min, H2 flow rate was 3 ml / min, and the remainder was N2 flow rate. The specific regeneration process was as follows: After the C3 catalyst reacted for 8 h, the reaction gas was shut off, and the temperature was lowered to 500 °C under a nitrogen atmosphere. Then, a 20% O2 / N2 mixture was introduced for calcination for 30 min to remove carbon deposits on the catalyst. After calcination, the temperature was further increased to 600 °C under a nitrogen atmosphere, and then treated in situ with 20% H2 / Ar for 2 h. The temperature was then lowered to 550 °C under a nitrogen atmosphere for further reaction. The above reaction, calcination, and reduction processes were then repeated. The catalyst was recycled four times. The initial propane conversion rate of the catalyst was 33% and the propylene selectivity was 98.5% during the initial test. After four cycles of air roasting and regeneration at 500°C, the propylene selectivity was still 98%, but the propane conversion rate was only 21%. The catalyst could not achieve redispersion of Pt after regeneration.

[0071] Table 2: Regeneration cycle performance of catalyst in propane dehydrogenation.

[0072]

[0073] The data in Table 2 indicate that the catalyst prepared in this invention exhibits excellent regeneration performance in propane dehydrogenation regeneration cycles and resists sintering in air. Compared to the catalysts in Comparative Examples 1 and 3, the catalyst prepared in this invention significantly improves the stability of the regeneration cycle, and its activity is almost fully recovered after air regeneration. Furthermore, its activity at 600℃ is far superior to that of the catalyst in Comparative Example 2 in terms of selectivity and stability. Characterization results show that after multiple regeneration cycles at 500℃, the metal particles in the catalyst did not undergo significant growth. Furthermore, no Pt-Pt was observed by EAXFS characterization. The absence of Pt sintering after multiple cycles in this material indicates stable catalytic activity in propane dehydrogenation.

[0074] Compared with the catalyst of Example 1 and the PtSn / Al2O3 catalyst provided in Comparative Example 3, the catalyst provided by the present invention greatly improves the regeneration stability of the catalyst and has excellent regeneration cycle performance.

Claims

1. A method for regenerating a supported high-entropy Pt catalyst for propane dehydrogenation to propylene, characterized in that: This involves calcining a silicon dioxide-supported high-entropy Pt catalyst, used in the propane dehydrogenation to propylene reaction, in air or an oxygen-nitrogen mixture at 200-600°C for 0.5-6 h, followed by reduction in a reducing atmosphere at 500-700°C for 0.5-4 h. h yields a regenerated supported high-entropy Pt catalyst; wherein the volume concentration of H2 in the reducing atmosphere is 5-100%; the supported high-entropy Pt catalyst comprises a support and a metal active component, wherein the metal active component comprises Pt, Zn, Mn, and Al, wherein the Al metal element is at least two of Fe, Co, Ni, Cu, Ga, Ge, In, and Sn; the mass percentage of Pt in the catalyst is 0.1-3 wt.%; among the metal elements in the supported high-entropy Pt catalyst, the atomic percentage of Pt is 5-30%, the atomic percentage of Zn is 10-30%, the atomic percentage of Mn is 10-30%, and the atomic percentage of Al metal element is 15-65%; The method for preparing the supported high-entropy Pt catalyst includes the following steps: S1. A metal precursor salt and a solvent are mixed to obtain a metal precursor salt solution; S2 uses co-impregnation or stepwise impregnation methods to impregnate the metal precursor salt onto the carrier to obtain a mixture; S3 The mixture is dried, calcined and reduced to obtain the supported high-entropy Pt catalyst.

2. The regeneration preparation method according to claim 1, characterized in that: The concentration of the metal precursor salt solution is 0.003-0.3 mol / L.

3. The regeneration preparation method according to claim 1, characterized in that: In step S3, the roasting atmosphere is air, nitrogen, or argon, the roasting temperature is 300-700 ℃, and the roasting time is 2-6 h; in step S3, the reducing atmosphere is hydrogen, carbon monoxide, or nitrogen, the reduction temperature is 500-700 ℃, and the reduction time is 0.5-4 h.

4. The application of the regeneration preparation method according to claim 1 in the preparation of propylene from propane dehydrogenation.

5. The application as described in claim 4, characterized in that: The method includes passing propane or a propane-containing mixture into a fixed-bed reactor containing a supported high-entropy Pt catalyst for catalytic reaction. After the catalytic reaction, the mixture is switched to air or an oxygen-nitrogen mixture for in-situ regeneration according to the regeneration preparation method described in claim 1, and then switched back to propane or a propane-containing mixture for propane dehydrogenation to propylene reaction.

6. The application as described in claim 5, characterized in that: The mixed gas also includes hydrogen and / or diluent nitrogen.

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