CuPt / Zn-HPS-1 catalyst, its preparation method and application

Abstract

The application discloses a CuPt / Zn-HPS-1 catalyst and a preparation method and application thereof, and the preparation method comprises the following steps: S1, preparing a Silicate-1 molecular sieve; S2, preparing a Zn modified hollow porous Silicate-1 molecular sieve by taking the Silicate-1 molecular sieve as a crystal nucleus to obtain Zn-HPS-1; S3, performing atomic layer deposition of platinum on the Zn-HPS-1 to obtain Pt / Zn-HPS-1; and S4, after the Pt / Zn-HPS-1 is impregnated with Cu, performing carbonization treatment under an air atmosphere for 1-2 hours to obtain the CuPt / Zn-HPS-1 catalyst. The CuPt / Zn-HPS-1 catalyst prepared by the application can exhibit good dehydrogenation activity by regulating the Pt particles resistant to sintering through the surface Cu substance, which is beneficial to enhancing the strength of Lewis acid Zn 2+ sites and promoting the activation of C-H in propane dehydrogenation, so that the CuPt / Zn-HPS-1 catalyst prepared by the application can exhibit relatively stable dehydrogenation activity in a cyclic regeneration reaction under an industrial equivalent feed.

Description

Technical Field

[0001] This invention relates to the field of petrochemical catalyst technology, and in particular to a CuPt / Zn-HPS-1 catalyst, its preparation method, and its application. Background Technology

[0002] Propylene is a crucial raw material for the production of chemical intermediates such as propylene oxide, polypropylene, acrylic acid, and isopropanol. Traditional propylene production processes (petroleum cracking and refinery gas cracking) suffer from drawbacks including high energy consumption, low yield, high cost, and environmental pollution. To fill the supply-demand gap in propylene, low-cost and sustainable propane direct dehydrogenation (PDH) technology has attracted significant attention. Innovations in shale gas extraction methods provide a large availability of propane feedstock, and PDH technology holds the promise of converting propane into high-value-added propylene and addressing the energy supply mismatch issue.

[0003] Currently, mainstream commercial PDH catalysts include noble metal-based (Pt) and non-noble metal oxide-based (CrO) catalysts. x Catalysts. The high cost of Pt poses challenges to large-scale applications. Furthermore, in high-temperature catalytic reactions, Pt materials are prone to sintering and migration, leading to Pt deactivation and a rapid decrease in PDH catalytic activity. CrO x The inherent toxicity of catalysts can cause environmental pollution, and the irreversible deactivation of active materials in PDH reactions leads to a loss of PDH activity. Furthermore, frequent replacement of deactivated catalysts can result in cumbersome operations. Therefore, developing a low-cost, environmentally friendly, efficient, and long-life catalyst is of great significance in propane dehydrogenation technology.

[0004] In recent years, Zn-based catalysts have been increasingly used in propane dehydrogenation reactions due to their low cost and environmental friendliness. However, the development of Zn-based catalysts still faces the following problems: 1) Zn evaporation; 2) poor metal site dispersion; 3) poor stability. Possible reasons are as follows:

[0005] 1) The interaction strength between the catalyst support and the metal is low, and no covalent bonds are formed. During high-temperature reactions, the active metal material sinters or migrates and aggregates into large particles, leading to a reduction in catalytic centers and a rapid loss of catalytic activity.

[0006] 2) The catalyst synthesis strategy affects the size and dispersion of the formed metal active sites. Wet impregnation often produces large-particle metals or metal oxides, which can exacerbate side reactions in PDH.

[0007] 3) Controllable synthesis of Lewis acid active site metal oxide catalysts with suitable strength. Excessive Lewis acid sites can lead to carbon deposition, while insufficient sites result in limited catalytic activation of CH bonds and lower dehydrogenation activity. Summary of the Invention

[0008] To address the above-mentioned problems, the present invention aims to provide a CuPt / Zn-HPS-1 catalyst, its preparation method, and its application.

[0009] The technical solution of the present invention is as follows:

[0010] On the one hand, a method for preparing a CuPt / Zn-HPS-1 catalyst is provided, comprising the following steps:

[0011] S1: Prepare Silicate-1 molecular sieve;

[0012] S2: Using the Silicate-1 molecular sieve as a crystal nucleus, Zn-modified hollow porous Silicate-1 molecular sieve is prepared to obtain Zn-HPS-1;

[0013] S3: Perform platinum atomic layer deposition on the Zn-HPS-1 to obtain Pt / Zn-HPS-1;

[0014] S4: The Pt / Zn-HPS-1 catalyst is impregnated with Cu and then carbonized in air for 1-2 hours to obtain the CuPt / Zn-HPS-1 catalyst.

[0015] Preferably, in step S1, the Silicate-1 molecular sieve is prepared by the following steps:

[0016] S11: Add 1-8 mL of tetrapropylammonium hydroxide to 1-100 mL of deionized water, then add 1-10 mL of tetraethyl orthosilicate, stir for 1-10 h to obtain a mixed solution;

[0017] S12: Add the mixed solution to a hydrothermal reactor and react at 50-200°C for 1-100 hours;

[0018] S13: Centrifuge, wash and dry the precipitate synthesized by the hydrothermal reaction;

[0019] S14: After grinding the dried solid, carbonize it in air at 500-600℃ for 1-10 hours to obtain the Silicate-1 molecular sieve.

[0020] Preferably, in step S13, when washing, deionized water is used first, followed by rinsing with anhydrous ethanol; when drying, the product is dried at 25–100°C for 1–24 hours.

[0021] Preferably, step S2, which uses the Silicate-1 molecular sieve as a crystal nucleus to prepare Zn-modified hollow porous Silicate-1 molecular sieve, specifically includes the following sub-steps:

[0022] S21: Dissolve 0.1-1 mL of ethylenediamine in 0.1-3 mL of deionized water, then add 0-0.4 g of zinc precursor to obtain solution A;

[0023] S22: Add 1-5g of Silicate-1 molecular sieve to 1-10mL of deionized water and stir to obtain solution B;

[0024] S23: Add solution A to solution B and dry to obtain a solid;

[0025] S24: The solid is carbonized in an air atmosphere, cooled to room temperature, and then reduced under a mixed gas of hydrogen and argon to obtain Zn-HPS-1.

[0026] Preferably, in step S21, the zinc precursor is zinc sulfate, zinc nitrate, or zinc acetate; in step S24, when performing carbonization treatment, carbonization is carried out at 500-600°C for 0.5-10 hours; when performing reduction treatment, reduction is carried out at 500-600°C for 0.5-10 hours.

[0027] Preferably, step S3, which involves platinum atomic layer deposition of the Zn-HPS-1, specifically includes the following sub-steps:

[0028] S31: Disperse 0.1-1g of Zn-HPS-1 in 0.1-1.5mL of solvent, mix well, drop onto a glass slide and let it dry naturally;

[0029] S32: The trimethyl(methylcyclopentadienyl)platinum(IV) precursor is heated to generate steam;

[0030] S33: Expose the sample obtained in step S31 to gas and perform platinum atomic layer deposition at 300°C; when exposing to gas, first expose the vapor from step S32 for 2s, and then sequentially purge with N2 for 20s, O2 for 2s, and N2 for 20s.

[0031] S34: Repeat step S33 multiple times to obtain the Pt / Zn-HPS-1.

[0032] Preferably, in step S4, when impregnating Cu with Pt / Zn-HPS-1, the following sub-steps are specifically included: taking 0.1-0.7g of Pt / Zn-HPS-1 and adding it to 1-10mL of solvent, then adding 0.04-0.16g of polyvinylpyrrolidone and 0.01-0.04g of copper precursor, stirring for 1-2h, and then drying to obtain the sample after impregnation of Cu with Pt / Zn-HPS-1.

[0033] Preferably, the copper precursor is copper acetate, copper sulfate, copper nitrate, or copper chloride.

[0034] On the other hand, CuPt / Zn-HPS-1 catalysts prepared by any of the above methods are also provided, and their application in propane dehydrogenation is also provided.

[0035] The beneficial effects of this invention are:

[0036] This invention modulates the anti-sintering Pt particles through surface Cu material, which is beneficial for enhancing Lewis acid Zn. 2+ The strength of the site promotes the activation of CH in propane dehydrogenation, enabling the CuPt / Zn-HPS-1 catalyst prepared in this invention to exhibit good dehydrogenation activity. In the cyclic regeneration reaction carried out under industrial-grade feed conditions, it can exhibit relatively stable dehydrogenation activity. Moreover, the preparation method of this invention is simple, relatively low-cost, and has good reproducibility, giving it a cost-effective advantage. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 The XRD patterns of Pt / Zn-HPS-1 and CuPt / Zn-HPS-1 catalysts in the comparative examples and embodiments of this invention are shown below.

[0039] Figure 2 These are TEM images and corresponding particle size distribution histograms for comparative examples and embodiments of the present invention; wherein, Figure 2 (a) is the TEM image of Pt / Zn-HPS-1. Figure 2 (b) is the corresponding particle size distribution histogram of Pt / Zn-HPS-1. Figure 2 (c) is a TEM image of CuPt / Zn-HPS-1. Figure 2 (d) is the corresponding particle size distribution histogram of CuPt / Zn-HPS-1;

[0040] Figure 3 The UV-Vis spectra of the Zn-HPS-1 and Pt / Zn-HPS-1 catalysts in the comparative examples of this invention are shown.

[0041] Figure 4 This is a schematic diagram showing the performance comparison results of PDH in the comparative examples and embodiments of the present invention;

[0042] Figure 5This is a schematic diagram showing the comparison results of the deactivation constants of the comparative examples and embodiments of the present invention;

[0043] Figure 6 This is a graph showing the cyclic regeneration catalytic performance of the comparative example Pt / Zn-HPS-1 of this invention; wherein, Figure 6 (a) is a graph showing the catalytic performance of the Pt / Zn-HPS-1 catalyst during cyclic regeneration. Figure 6 (b) is a TEM image of the Pt / Zn-HPS-1 catalyst after 40 hours of cyclic regeneration. Figure 6 (c) is a histogram of nanoparticle size distribution based on TEM;

[0044] Figure 7 This is a graph showing the cyclic regeneration catalytic performance of CuPt / Zn-HPS-1, a comparative example of this invention; wherein, Figure 7 (a) is a graph showing the catalytic performance of CuPt / Zn-HPS-1 catalyst during cyclic regeneration. Figure 7 (b) is a TEM image of the CuPt / Zn-HPS-1 catalyst after 40 hours of cyclic regeneration. Figure 7 (c) is a histogram of nanoparticle size distribution based on TEM. Detailed Implementation

[0045] The present invention will be further described below with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and technical features described in this application can be combined with each other. It should also be pointed out that, unless otherwise indicated, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. The terms "comprising" or "including" and similar words used in this invention refer to elements or objects preceding the word that encompass the elements or objects listed following the word and their equivalents, without excluding other elements or objects.

[0046] On one hand, the present invention provides a method for preparing a CuPt / Zn-HPS-1 catalyst, comprising the following steps:

[0047] S1: Prepare Silicate-1 molecular sieve.

[0048] In one specific embodiment, the Silicate-1 molecular sieve is prepared by the following steps:

[0049] S11: Add 1-8 mL of tetrapropylammonium hydroxide to 1-100 mL of deionized water, then add 1-10 mL of tetraethyl orthosilicate, stir for 1-10 h to obtain a mixed solution;

[0050] S12: Add the mixed solution to a hydrothermal reactor and react at 50-200°C for 1-100 hours;

[0051] S13: Centrifuge, wash and dry the precipitate synthesized by hydrothermal reaction; optionally, when washing, first wash with deionized water and then rinse with anhydrous ethanol; when drying, dry at 25-100℃ for 1-24 hours.

[0052] S14: After grinding the dried solid, carbonize it in air at 500-600℃ for 1-10 hours to obtain the Silicate-1 molecular sieve.

[0053] In the above embodiments, the carbonization process is carried out in an air atmosphere, which removes the tetrapropylammonium hydroxide template agent. If other atmospheres, such as nitrogen, are used, carbon residue will remain, affecting the performance of the finished product.

[0054] It should be noted that the above embodiments are merely preferred methods for preparing Silicate-1 molecular sieves according to the present invention. Other methods for preparing Silicate-1 molecular sieves in the prior art, besides those described above, are also applicable to the present invention. When using the present invention, existing Silicate-1 molecular sieves can also be directly used for subsequent steps.

[0055] S2: Using the Silicate-1 molecular sieve as a crystal nucleus, Zn-modified hollow porous Silicate-1 molecular sieve is prepared to obtain Zn-HPS-1.

[0056] In a specific embodiment, the preparation of Zn-modified hollow porous Silicate-1 molecular sieves using the Silicate-1 molecular sieve as a crystal nucleus specifically includes the following sub-steps:

[0057] S21: Dissolve 0.1-1 mL of ethylenediamine in 0.1-3 mL of deionized water, then add 0-0.4 g of zinc precursor to obtain solution A; optionally, the zinc precursor is zinc sulfate, zinc nitrate or zinc acetate.

[0058] S22: Add 1-5g of Silicate-1 molecular sieve to 1-10mL of deionized water and stir to obtain solution B;

[0059] S23: Add solution A to solution B and dry to obtain a solid;

[0060] S24: The solid is carbonized in an air atmosphere, cooled to room temperature, and then reduced under a mixed gas of hydrogen and argon to obtain Zn-HPS-1.

[0061] In the above embodiments, the present invention prepares Zn-modified hollow porous Silicate-1 molecular sieves by using the Silicate-1 molecular sieve as a crystal nucleus, so that the Silicate-1 molecular sieve is subjected to Zn... 2+ After modification, the synthesized hollow porous structure is beneficial for mass transfer between reactants and products in the catalytic reaction, and the introduced Zn 2+ As a Lewis acid site, it can promote the dissociation of CH in propane. Furthermore, the Lewis acid site Zn... 2+ It is beneficial for anchoring metal Pt and promotes the dispersion of Pt.

[0062] In one specific embodiment, the carbonization process is carried out at 500–600°C for 0.5–10 hours; the reduction process is carried out at 500–600°C for 0.5–10 hours.

[0063] S3: Perform platinum atomic layer deposition on the Zn-HPS-1 to obtain Pt / Zn-HPS-1.

[0064] In a specific embodiment, the platinum atomic layer deposition of the Zn-HPS-1 specifically includes the following sub-steps:

[0065] S31: Disperse 0.1-1g of Zn-HPS-1 in 0.1-1.5mL of solvent, mix well, drop onto a glass slide and let it dry naturally;

[0066] S32: The trimethyl(methylcyclopentadienyl)platinum(IV) precursor is heated to generate steam; optionally, it is heated to 65°C to generate steam;

[0067] S33: Expose the sample obtained in step S31 to gas and perform platinum atomic layer deposition at 300°C; when exposing to gas, first expose the vapor from step S32 for 2s, and then sequentially purge with N2 for 20s, O2 for 2s, and N2 for 20s.

[0068] S34: Repeat step S33 multiple times to obtain the Pt / Zn-HPS-1; optionally, repeat step S33 5-15 times.

[0069] In the above embodiments, the present invention utilizes Pt ALD to achieve surface-controllable synthesis of small-sized nanoparticles, and the introduction of Pt can regulate the Lewis acid Zn. 2+ The increased Lewis acid strength of Pt particles promotes the dissociation of CH4. Furthermore, the presence of Pt particles facilitates the recombination of H2 during propane dehydrogenation, accelerating the formation of reaction products and enhancing propylene selectivity.

[0070] S4: The Pt / Zn-HPS-1 catalyst is impregnated with Cu and then carbonized in air for 1-2 hours to obtain the CuPt / Zn-HPS-1 catalyst.

[0071] In a specific embodiment, the process of impregnating Cu with Pt / Zn-HPS-1 includes the following sub-steps: 0.1–0.7 g of Pt / Zn-HPS-1 is added to 1–10 mL of solvent, followed by the addition of 0.04–0.16 g of polyvinylpyrrolidone and 0.01–0.04 g of copper precursor. Optionally, the copper precursor is copper acetate, copper sulfate, copper nitrate, or copper chloride. After stirring for 1–2 h, the mixture is dried to obtain the sample impregnated with Cu using Pt / Zn-HPS-1.

[0072] In the above embodiments, in addition to adding copper precursor, polyvinylpyrrolidone was also added when impregnating Cu. Polyvinylpyrrolidone can disperse copper precursor in solution, avoid the formation of Cu agglomerates after drying, and thus generate large Cu particles during carbonization.

[0073] In the above embodiments, the present invention introduces Cu material into the interface of Pt particles, which can suppress the sintering and migration aggregation of Pt particles in high-temperature catalytic reactions and alleviate carbon deposition side reactions and catalyst deactivation in PDH reactions.

[0074] On the other hand, the present invention also provides a CuPt / Zn-HPS-1 catalyst prepared by any of the above preparation methods and its application in propane dehydrogenation.

[0075] Example 1

[0076] A CuPt / Zn-HPS-1 catalyst was prepared using the following steps:

[0077] (1) Preparation of S-1 (Silicate-1 molecular sieve)

[0078] Add 8.072 mL of TPAOH to 25.2 mL of deionized water (DI), then add 9.0 mL of TEOS, and stir for 6 hours at 300 rpm. Add the mixture to a 100 mL hydrothermal reactor and react in an oven at 170 °C for 96 hours. The precipitate synthesized by the hydrothermal reaction is centrifuged, washed with deionized water, rinsed with anhydrous ethanol, and then dried in an oven at 25–100 °C for 12 hours. The dried solid is then ground and carbonized in air at 550 °C for 8 hours to obtain S-1.

[0079] (2) Preparation of Zn-HPS-1

[0080] 0.5 mL of ethylenediamine (EDA) was dissolved in 2 mL of DI, followed by the addition of 0.0784 g of Zn(OAc)₂·2H₂O, denoted as solution A. 1 g of S⁻¹ was added to 10 mL of DI, and the mixture was stirred at 300 rpm for 2 h on a magnetic stirrer. Subsequently, solution A was added, and the solution was evaporated and dried in an oven at 80 °C for 12 h. The dried solid was ground and carbonized at 550 °C for 2 h in air, then cooled to room temperature and reduced at 550 °C for 1 h under 20 vol.% H₂ / Ar conditions to obtain Zn-HPS⁻¹.

[0081] (3) Preparation of Pt / Zn-HPS-1

[0082] 0.8 g of Zn-HPS-1 was dispersed in a mixed solution of 1.5 mL isopropanol (IPA) and 1.5 mL DI, and then sonicated for 0.5 h. The mixed solution was then dropped onto a glass slide and allowed to air dry. The trimethyl(methylcyclopentadienyl)platinum(IV) (MeCpPtMe3) precursor was heated to 65 °C to generate vapor. One Pt ALD cycle involved gas exposure of the sample in the following sequence: exposure to vapor MeCpPtMe3 (2 s), N2 purging (20 s), O2 purging (2 s), and N2 purging (20 s). Finally, 10 Pt ALD depositions were performed to deposit platinum onto Zn-HPS-1 at 300 °C to obtain the Pt / Zn-HPS-1.

[0083] (4) Preparation of CuPt / Zn-HPS-1

[0084] 0.7 g of Pt / Zn-HPS-1 was added to 10 mL of anhydrous ethanol, followed by 0.1 g of polyvinylpyrrolidone (PVP) and 0.025 g of Cu(OAc)₂·H₂O, and stirred for 2 h. The solution was then evaporated and dried in an oven at 80 °C. The dried solid was ground and carbonized in air for 2 h to obtain CuPt / Zn-HPS-1.

[0085] It should be noted that the above embodiment is only a preferred embodiment of the present invention. The present invention has also successfully prepared CuPt / Zn-HPS-1 with other corresponding parameters by changing the amount of compounds used in each step, the type of compounds (Silicate-1 molecular sieve, zinc precursor, copper precursor, solvent, etc.), reaction temperature, reaction time, deposition times, and other parameters.

[0086] Comparative Example 1

[0087] Unlike Example 1, this comparative example directly loads Pt onto S-1. That is, it proceeds directly to step (3) after step (1): 0.8 g of S-1 is dispersed in a mixed solution of 1.5 mL isopropanol (IPA) and 1.5 mL DI, and then sonicated for 0.5 h. Subsequently, the mixed solution is dropped onto a glass slide and allowed to air dry. The trimethyl(methylcyclopentadienyl)platinum(IV) (MeCpPtMe3) precursor is heated to 65 °C to generate vapor. One Pt ALD cycle involves gas exposure of the sample in the following sequence: exposure to vapor MeCpPtMe3 (2 s), N2 purging (20 s), O2 purging (2 s), and N2 purging (20 s). Finally, 10 Pt ALD depositions are performed to deposit platinum onto S-1 at 300 °C to obtain Pt / S-1.

[0088] Comparative Example 2

[0089] Unlike Example 1, this comparative example ends after obtaining Zn-HPS-1 in step (2), and is no longer modified with Pt and Cu.

[0090] Comparative Example 3

[0091] Unlike Example 1, this comparative example ends after obtaining Pt / Zn-HPS-1 in step (3) and is no longer modified with Cu.

[0092] The products of Example 1 and each comparative example were characterized using XRD patterns. The XRD patterns of Pt / Zn-HPS-1 and CuPt / Zn-HPS-1 are shown below. Figure 1 As shown. From Figure 1 It can be seen that the diffraction peaks at 7.9°, 8.9°, 23.2°, 24.0°, and 24.5° belong to the typical zeolite inverted framework (MFI) structure of Silicalite-1 (PDF#44-0696). Furthermore, no diffraction peaks clearly attributed to metallic substances are present in the XRD pattern, indicating that the metallic substances in the catalyst are well dispersed or the content of the metallic substances is below the detection limit of XRD. This suggests that after the introduction of Cu, no Cu metal particles or oxides are formed, and Cu remains in a highly dispersed form within the formed catalyst.

[0093] TEM images were used to characterize the products of Example 1 and each comparative example. The TEM images and size distribution results of Pt / Zn-HPS-1 and CuPt / Zn-HPS-1 are shown below. Figure 2 As shown. From Figure 2It can be seen that the Pt nanoparticles in Pt / Zn-HPS-1 are located on the catalyst surface and have an average particle size of 1.4 nm. With the addition of Cu and the subsequent carbonization process, the Pt nanoparticles on the surface of CuPt / Zn-HPS-1 are more prominent and their size increases to 3.3 nm.

[0094] The products of Example 1 and each comparative example were characterized using ultraviolet-visible spectroscopy (UV-vis), with the results for Zn-HPS-1 and Pt / Zn-HPS-1 as follows: Figure 3 As shown. From Figure 3 It can be seen that the absorption bands of Zn-HPS-1 and Pt / Zn-HPS-1 are located at 220 nm, which is attributed to the framework Zn. 2+ Furthermore, the introduction of Pt significantly enhanced the Zn content. 2+ The absorption intensity at 220 nm indicates that the introduction of Pt can alter the coordination environment and electronic structure of Zn. Furthermore, no absorption band at 370 nm belonging to bulk zinc oxide was found in the UV-Vis spectra of Zn-HPS-1 and Pt / Zn-HPS-1, suggesting the absence of large ZnO nanoparticles in the catalyst.

[0095] PDH reaction tests were performed on the products of Example 1 and each comparative example: The catalytic activity of propane dehydrogenation was evaluated in a fixed-bed microreactor. The stainless steel reaction tube had an inner diameter of 12 mm, and a certain amount of catalyst mixed with quartz sand was placed in the isothermal zone of the stainless steel reaction tube. Subsequently, the reaction apparatus was heated to 550 °C under 20% H2 / N2 purging and activated for 1 h. After N2 purging for 10 min, the reaction gas (5% C3H8 / N2, 40 mL / min) was switched to carry out the propane dehydrogenation reaction. The gaseous reaction products were analyzed by a gas chromatograph (Shimadzu GC-2014) equipped with an HP / AL-S column using a flame ionization detector (FID).

[0096] The catalyst was catalytically regenerated using an industrial feed (67% C3H8 / N2, 9 mL / min). The regeneration process consisted of 50 mL / min cycles. -1 The coking reaction was carried out at 550℃ for 30 min under flowing air, followed by 10 min of N2 (100 mL / min) purging, 30 min of activation with 20% H2 / Ar (100 mL / min), and 10 min of N2 (100 mL / min) purging. The propane conversion, propylene selectivity, and propylene yield were calculated as follows:

[0097]

[0098]

[0099] Yield = Conversion × Selectivity (3)

[0100]

[0101] nC x H y The reaction gas outlet composition (μmol / min) was quantitatively determined using an external standard curve in GC-2014. -1 ).

[0102] PDH performance test (550℃, C3H8 / N2=2 / 38, 40mL min) -1 WHSV = 0.47h -1 The result is as follows Figure 4 , Figure 5 As shown in Table 1:

[0103] Table 1. Test results of propane dehydrogenation performance of the catalyst

[0104]

[0105] from Figure 4 , Figure 5 As shown in Table 1, the CuPt / Zn-HPS-1 prepared in this invention exhibits good dehydrogenation activity and stability (initial propane conversion 30.4%, initial propylene selectivity 99.0%, initial propylene yield 30.1%, K...). d =0.027h -1 This is because the CuPt / Zn-HPS-1 described in this invention introduces active Zn through in-situ recrystallization. 2+ Furthermore, Zn is enhanced by surface deposition of Pt particles to construct a favorable hollow porous structure. 2+ The activity of the site; finally, in order to suppress the carbon deposition and catalyst deactivation caused by the sintering and migration of Pt particles deposited on the surface during high-temperature catalytic dehydrogenation, interfacial Cu was introduced to regulate the geometry and electronic properties of Pt, thus significantly improving its stability.

[0106] Compared to the CuPt / Zn-HPS-1 catalyst prepared in this invention, the Pt / S-1 catalyst in Comparative Example 1 exhibits poorer activity. This may be due to the limited catalytically active material in the catalyst, resulting in limited catalytic activity and poor PDH activity. The Zn-HPS-1 catalyst in Comparative Example 2 shows relatively low initial catalytic performance and low propane conversion rate after 6 hours of average performance, and Kc is also low after 6 hours of reaction. dThe values ​​are relatively large. Although the initial catalytic performance and 6-hour average propane conversion of the Pt / Zn-HPS-1 catalyst in Comparative Example 3 are comparable to those of the present invention, its Kt after 6 hours of reaction is significantly lower. d The values ​​are relatively large, and the stability is poor.

[0107] The regeneration cycle performance of Example 1 and each comparative example product was tested in air (50 mL min). -1 ) burn in 20% H2 / N2 (100mL min) and pass through 20% H2 / N2 (100mL min) -1 The activated catalyst regains its activity in the subsequent dehydrogenation reaction.

[0108] The regeneration cycle performance results of Pt / Zn-HPS-1 in Comparative Example 3 are as follows: Figure 6 As shown, after 40 hours of reaction and regeneration, the catalyst deactivation constant is 0.0135 h⁻¹. -1 The catalytic reaction and the catalyst after three cycles were characterized by TEM, showing that the surface Pt particle size increased to 4.66 nm. Compared to the fresh catalyst, the particle size increased by 3.26 nm after the catalytic reaction. This suggests that the loss of activity in the PDH reaction may be due to coking side reactions caused by the increased Pt particle size and the presence of Zn. 2+ Changes in coordination structure and electron configuration at active sites. Furthermore, calcination can effectively restore catalyst activity and extend its lifespan.

[0109] The regeneration cycle performance results of CuPt / Zn-HPS-1 in Example 1 are as follows: Figure 7 As shown, after 40 h of reaction and regeneration, the deactivation constant of the CuPt / Zn-HPS-1 catalyst is 0.0098 h. -1 Compared to Pt / Zn-HPS-1, the concentration decreased by 27.41%, indicating that the introduction of Cu interface modulation in this invention can enhance the stability of the catalyst. TEM characterization of the catalytic reaction and the catalyst after three cycles showed that the surface Pt particle size increased to 3.77 nm. Compared to the fresh catalyst, the particle size increased by 0.47 nm after the catalytic reaction. This indicates that the introduction of Cu enables geometric modulation and electronic structure optimization of Pt particles, suppressing Pt sintering and migration aggregation in the PDH reaction, and improving dehydrogenation stability. Furthermore, calcination can effectively restore the catalyst activity and extend its service life.

[0110] It should be noted that the above are only test results of some embodiments and comparative examples of the present invention. Compared with the corresponding Pt / Zn-HPS-1 comparative examples, the CuPt / Zn-HPS-1 prepared in other embodiments of the present invention also shows significant performance improvement. The optimal CuPt / Zn-HPS-1 catalyst has a Cu loading of 1.11 wt%, a Pt loading of 0.022 wt%, and a Zn loading of 3.18 wt%.

[0111] In summary, this invention exhibits excellent catalytic activity, high propylene selectivity, and strong stability. Compared with existing technologies, this invention represents a significant advancement.

[0112] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing a CuPt / Zn-HPS-1 catalyst, characterized in that, Includes the following steps: S1: Prepare Silicate-1 molecular sieve; S2: Using the Silicate-1 molecular sieve as a crystal nucleus, Zn-modified hollow porous Silicate-1 molecular sieve is prepared to obtain Zn-HPS-1; Specifically, it includes the following sub-steps: S21: Dissolve 0.1–1 mL of ethylenediamine in 0.1–3 mL of deionized water, then add 0–0.4 g of zinc precursor to obtain solution A; S22: Add 1-5 g of Silicate-1 molecular sieve to 1-10 mL of deionized water and stir to obtain solution B; S23: Add solution A to solution B and dry to obtain a solid; S24: The solid is carbonized in an air atmosphere, cooled to room temperature, and then reduced under a mixed gas of hydrogen and argon to obtain Zn-HPS-1; S3: Perform platinum atomic layer deposition on the Zn-HPS-1 to obtain Pt / Zn-HPS-1; Specifically, it includes the following sub-steps: S31: Disperse 0.1–1 g of Zn-HPS-1 in 0.1–1.5 mL of solvent, mix well, drop onto a glass slide and allow to air dry. S32: The trimethyl(methylcyclopentadienyl)platinum(IV) precursor is heated to generate vapor; S33: Expose the sample obtained in step S31 to gas and perform platinum atomic layer deposition at 300 °C; when exposing to gas, first expose the vapor from step S32 for 2 s, and then sequentially purge with N2 for 20 s, O2 for 2 s, and N2 for 20 s. S34: Repeat step S33 multiple times to obtain the Pt / Zn-HPS-1; S4: The Pt / Zn-HPS-1 catalyst is impregnated with Cu and then carbonized in air for 1-2 h to obtain the CuPt / Zn-HPS-1 catalyst. The process of impregnating Cu with Pt / Zn-HPS-1 includes the following sub-steps: 0.1–0.7 g of Pt / Zn-HPS-1 is added to 1–10 mL of solvent, followed by the addition of 0.04–0.16 g of polyvinylpyrrolidone and 0.01–0.04 g of copper precursor. After stirring for 1–2 h, the mixture is dried to obtain the sample impregnated with Cu using Pt / Zn-HPS-1.

2. The method for preparing the CuPt / Zn-HPS-1 catalyst according to claim 1, characterized in that, In step S1, the Silicate-1 molecular sieve is prepared through the following steps: S11: Add 1-8 mL of tetrapropylammonium hydroxide to 1-100 mL of deionized water, then add 1-10 mL of tetraethyl orthosilicate, stir for 1-10 h to obtain a mixed solution; S12: Add the mixed solution to a hydrothermal reactor and react at 50–200 °C for 1–100 h; S13: Centrifuge, wash and dry the precipitate synthesized by the hydrothermal reaction; S14: After grinding the dried solid, carbonize it in air at 500-600 °C for 1-10 h to obtain the Silicate-1 molecular sieve.

3. The method for preparing the CuPt / Zn-HPS-1 catalyst according to claim 2, characterized in that, In step S13, during washing, deionized water is used for washing first, followed by rinsing with anhydrous ethanol; during drying, the product is dried at 25–100 °C for 1–24 h.

4. The method for preparing the CuPt / Zn-HPS-1 catalyst according to claim 1, characterized in that, In step S21, the zinc precursor is zinc sulfate, zinc nitrate, or zinc acetate; in step S24, when performing carbonization treatment, carbonization is carried out at 500–600 °C for 0.5–10 h; when performing reduction treatment, reduction is carried out at 500–600 °C for 0.5–10 h.

5. The method for preparing the CuPt / Zn-HPS-1 catalyst according to claim 1, characterized in that, The copper precursor is copper acetate, copper sulfate, copper nitrate, or copper chloride.

6. A CuPt / Zn-HPS-1 catalyst, characterized in that, It was prepared using the preparation method of CuPt / Zn-HPS-1 catalyst according to any one of claims 1-5.

7. The application of the CuPt / Zn-HPS-1 catalyst as described in claim 6 in propane dehydrogenation.

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