A molecular sieve loaded high entropy alloy nanoparticle material and preparation method thereof

Abstract

The present invention discloses a molecular sieve-loaded high-entropy alloy nanoparticle material and a preparation method thereof, belonging to the field of nanomaterial technology. The preparation method comprises the following steps: adding a metal salt precursor to a polyvinyl pyrrolidone and L-ascorbic acid mixed polyol solution for reaction; then adding acetone to obtain high-entropy alloy nanoparticles; then uniformly mixing with a solvent and an alkaline solution, adding tetraethyl orthosilicate, stirring, and obtaining high-entropy alloy@silica powder; finally mixing and grinding it with tetrapropylammonium hydroxide, adding water and standing for crystallization, centrifuging and calcining the solid product to obtain. The present invention uses metal salt as raw material, polyvinyl pyrrolidone as a protective agent, utilizes a polyol reduction method to prepare high-entropy alloy nanoparticles, then prepares high-entropy alloy@silica by a Stober method, and finally obtains it by hydrothermal synthesis; the molecular sieve nanoparticles obtained by the present invention have small size, large specific surface area, strong catalytic activity, and good dispersion.

Description

Technical Field

[0001] The present invention relates to the technical field of nanomaterials, and in particular to a molecular sieve-loaded high-entropy alloy nanoparticle material and a preparation method thereof. Background Art

[0002] High-entropy alloys (HEAs) are a new class of alloy materials composed of five or more elements. Their multi-element nature offers broad opportunities for material discovery and performance optimization. Although the concept of HEAs has been around for a long time, research on HEA nanoparticles has only recently begun to gain momentum. The greatest challenge in synthesizing HEA nanoparticles lies in integrating multiple elements into a single nanoparticle. Due to differences in size and properties between the different elements, the alloys are prone to phase separation, resulting in a heterogeneous structure. Numerous synthetic methods have been proposed to prepare HEA nanoparticles with a single-phase solid solution structure. These include carbon thermal shock, vapor-phase spark discharge, rapid radiation heating, chemical synthesis, low-temperature electrochemical reconstruction, sputtering, transient electrosynthesis, plasma heating, microwave heating, laser heating, organic ligand crosslinking, and liquid metal fusion. However, due to the significant differences in physicochemical properties between the constituent elements, developing a universal synthesis method for HEA nanoparticles that can achieve the desired structure and properties is a challenge.

[0003] To effectively utilize high-entropy alloy nanoparticles, they need to be loaded onto a solid carrier. However, size reduction leads to a surge in the metal's surface energy, which in turn makes the nanoparticles loaded onto an open carrier thermodynamically unstable. Especially when the temperature exceeds the Tamman temperature, the nanoparticles are prone to leaching, sintering, and poisoning, resulting in the loss of their original structure and properties. To address these issues, researchers have begun to attempt to confine nanoparticles within the pores or cavities of solid carriers, immobilizing the nanoparticles through spatial confinement effects.

[0004] Molecular sieve is an inorganic nanoporous crystalline material composed of TO4 (where T refers to Si, Al or P) tetrahedrons. These tetrahedral structures are interconnected by sharing vertex oxygen atoms with each other, thereby forming unique three-dimensional pore structures such as rings, cages, and channels. Its notable features include high specific surface area, uniform and ordered microporous channels, and adjustable acidity and alkalinity. The ordered and adjustable microporous channels give molecular sieves unique selectivity: they can selectively allow specific molecules to enter or exit the channels based on the size, shape and polarity of the molecules. A large number of studies have shown that when molecular sieves are used as carriers of nanoparticles, they can effectively confine nanoparticles to channels or cavities, so molecular sieves have shown extraordinary effects in anchoring nanoparticles.

[0005] The type, size, and structure of the metal elements in molecular sieves can be adjusted through different synthesis strategies. Currently, researchers have developed a variety of synthesis strategies, covering various in-situ synthesis and post-processing synthesis methods. However, these methods involve the use of large amounts of solvents, which can easily lead to dissolution of high-entropy alloy nanoparticles and phase segregation, thereby changing the original structure and properties of the high-entropy alloy nanoparticles. Summary of the Invention

[0006] In order to solve the above technical problems, the purpose of the present invention is to provide a molecular sieve loaded high entropy alloy nanoparticle material and a preparation method thereof, so as to solve the problems of easy phase segregation, poor dispersion effect, and easy agglomeration during the preparation of existing molecular sieve loaded high entropy alloy nanoparticle materials.

[0007] The technical solution of the present invention to solve the above technical problems is as follows:

[0008] A method for preparing a molecular sieve-loaded high-entropy alloy nanoparticle material comprises the following steps:

[0009] (1) adding a metal salt precursor solution to a mixed polyol solution of polyvinyl pyrrolidone and L-ascorbic acid to react to prepare a high entropy alloy nanoparticle dispersion;

[0010] (2) adding acetone to the dispersion obtained in step (1), centrifuging, and obtaining high entropy alloy nanoparticles;

[0011] (3) uniformly mixing the high entropy alloy nanoparticles obtained in step (2) with a solvent and an alkaline solution, adding tetraethyl orthosilicate, stirring, and drying to obtain a high entropy alloy@silicon dioxide powder;

[0012] (4) The high entropy alloy@silica powder obtained in step (3) is first mixed with tetrapropylammonium hydroxide, ground, heated and dried, and then ultrapure water is added, allowed to stand for crystallization, and finally centrifuged and the solid product is calcined to obtain a high entropy alloy@MFI zeolite molecular sieve.

[0013] Furthermore, the metal salt in step (1) is at least five of palladium inorganic salt, platinum inorganic salt, rhodium inorganic salt, ruthenium inorganic salt, iridium inorganic salt, gold inorganic salt, copper inorganic salt, iron inorganic salt, cobalt inorganic salt and nickel inorganic salt; the concentration of each metal salt in the metal salt precursor solution is 0.01-0.015 mmol / mL, and the solvent is ethylene glycol.

[0014] Further, the palladium inorganic salt is any one of PdCl2, PdCl4, Na2PdCl4, Na2PdCl6, K2PdCl4 and K2PdCl6;

[0015] The platinum inorganic salt is any one of PtCl2, PtCl4, Na2PtCl6, Na2PtCl6·6H2O, Na2PtCl4·xH2O, K2PtCl4 and K2PtCl6;

[0016] The rhodium inorganic salt is any one of RhCl3, RhCl3·3H2O, RhCl3·xH2O and K3RhCl6;

[0017] The ruthenium inorganic salt is one of RuCl3, RuCl3·3H2O, RuCl3·xH2O, K2RuCl6 and K3RuCl6;

[0018] The iridium inorganic salt is any one of IrCl3, IrCl4, IrCl3·3H2O, IrCl3·xH2O, IrCl4·xH2O, Na2IrCl6·6H2O, Na3IrCl6·xH2O, H2IrCl6·xH2O and K3IrCl6;

[0019] The gold inorganic salt is any one of AuCl, NaAuCl4·2H2O and HAuCl4·3H2O;

[0020] The copper inorganic salt is any one of CuCl, CuCl2, CuCl2·H2O and CuCl2·2H2O;

[0021] The iron inorganic salt is any one of FeCl2, FeCl3, FeCl2·2H2O, FeCl2·4H2O, FeCl3·6H2O and FeCl2·xH2O;

[0022] The cobalt inorganic salt is any one of CoCl2, CoCl2·6H2O and CoCl2·xH2O;

[0023] The nickel inorganic salt is any one of NiCl2, NiCl2·6H2O and NiCl2·xH2O.

[0024] Furthermore, the molecular weight of polyvinyl pyrrolidone in step (1) is 2500-58000; the concentration of polyvinyl pyrrolidone in the mixed polyol solution of polyvinyl pyrrolidone and L-ascorbic acid is 0.001-0.4 g / mL, the concentration of L-ascorbic acid is 0.001-0.01 g / mL, and the solvent is ethylene glycol.

[0025] Furthermore, the structural formula of L-ascorbic acid is:

[0026] Furthermore, in step (1), the metal salt precursor solution is added to the reaction solution by dropwise injection at an injection rate of 0.005-3 mL / min. The reaction solution is preheated to 150-230° C. before addition. When all the metal salt precursor solution is dropwise injected into the reaction solution, the reaction is stopped.

[0027] The beneficial effects of adopting the above-mentioned further technical solution are as follows: the present invention controls the reduction rate of different metals during the synthesis process by dripping and injecting, thereby obtaining high-entropy alloy nanoparticles with uniform elemental composition and stability, and the size of the high-entropy alloy nanoparticles is between 5-20 nm, which increases the specific surface area of ​​the high-entropy alloy nanoparticles and provides more metal active sites, which can more effectively exert the synergistic effect between the high-entropy alloy components and greatly enhance the catalytic performance.

[0028] Furthermore, in step (2), the volume ratio of the dispersion to acetone is 1:5-1:10; the centrifugal speed is 8000-12000 rpm, and the time is 30-60 min.

[0029] Furthermore, in step (3), the mass volume ratio of tetraethyl orthosilicate, solvent and alkaline solution is 3-4g:50-100mL:5-7mL, the solvent is ethanol, and the alkaline solution is ammonia water; the stirring time is 6-12h; the drying temperature is 80-100°C, and the drying time is 5-24h.

[0030] Preferably, in step (3), the mass volume ratio of tetraethyl orthosilicate, solvent and alkaline solution is 3.4-3.5 g:80 mL:6 mL.

[0031] Furthermore, the structural formula of tetraethyl orthosilicate is:

[0032] Furthermore, the mass ratio of tetrapropylammonium hydroxide in step (4) to tetraethyl orthosilicate in step (3) is 0.5-1:3-4; the mass volume ratio of tetrapropylammonium hydroxide to water is 0.5-1g:200-1600μL; the temperature of the static crystallization is 120-200℃, and the time is 1-5d; the centrifugal speed is 8000-12000rpm, and the time is 30-60min; the calcination conditions are: in an air atmosphere, first heating to 500-600℃ at a heating rate of 2-10℃ / min, then keeping warm for 4-5h, and then cooling to room temperature.

[0033] The beneficial effects of adopting the above-mentioned further technical solution are as follows: the present invention controls the water content during the hydrothermal synthesis process to avoid the dissolution or agglomeration of high-entropy alloy nanoparticles, while reducing the amount of solvent used, thereby improving the safety of hydrothermal synthesis and reducing the generation of waste liquid.

[0034] Preferably, the mass ratio of tetrapropylammonium hydroxide in step (4) to tetraethyl orthosilicate in step (3) is 0.8-0.9:3.4-3.5; the mass volume ratio of tetrapropylammonium hydroxide to water is 0.8-0.9 g:200-1600 μL; and the calcination conditions are: in an air atmosphere, first heating to 550° C. at a heating rate of 2-10° C. / min, then keeping the temperature for 4-5 hours, and then cooling to room temperature.

[0035] Further, the structural formula of tetrapropylammonium hydroxide is:

[0036] A molecular sieve-loaded high-entropy alloy nanoparticle material is prepared by adopting the above preparation method.

[0037] The present invention has the following beneficial effects:

[0038] (1) The present invention uses a metal salt precursor as a raw material, polyvinyl pyrrolidone as a protective agent, L-ascorbic acid and ethylene glycol reducing agents as modifiers, and adopts a wet chemical method to prepare high-entropy alloy nanoparticles. The obtained high-entropy alloy nanoparticles are composed of more than five metal elements, and each metal element is evenly dispersed. The molar percentage of each metal element in the alloy is 5%-35%.

[0039] (2) The present invention adopts the method of dripping and injection to control the reduction rate of different metals during the synthesis process, thereby obtaining high-entropy alloy nanoparticles with uniform elemental composition and stability, and the size of the high-entropy alloy nanoparticles is between 5-20nm, which increases the specific surface area of ​​the high-entropy alloy nanoparticles and provides more metal active sites, which can more effectively exert the synergistic effect between the high-entropy alloy components and greatly enhance the catalytic performance.

[0040] (3) The present invention adopts a solid precursor stabilization method to synthesize molecular sieves, and stabilizes high entropy alloy nanoparticles by silica, so that after hydrothermal synthesis, the high entropy alloy nanoparticles can be uniformly confined in the molecular sieve and have ultra-high dispersion.

[0041] (4) The present invention controls the water content in the hydrothermal synthesis process to avoid the dissolution or agglomeration of high-entropy alloy nanoparticles, while reducing the amount of solvent used, which helps to improve the safety of hydrothermal synthesis and reduce the generation of waste liquid. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 1 is the HADDF-STEM image of the high entropy alloy nanoparticles in Example 1;

[0043] Figure 2 is a size distribution diagram of high entropy alloy nanoparticles in Example 1;

[0044] Figure 3Statistical diagram of the composition of high entropy alloy nanoparticles in Example 1;

[0045] Figure 4 This is the HADDF-STEM image of the high entropy alloy@silicon dioxide in Example 1;

[0046] Figure 5 This is the HADDF-STEM of the high entropy alloy@MFI zeolite molecular sieve in Example 1;

[0047] Figure 6 This is the HADDF-STEM image of the high entropy alloy / MFI zeolite molecular sieve in Comparative Example 1. DETAILED DESCRIPTION

[0048] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples are only used to explain the present invention and are not intended to limit the scope of the invention. In the embodiments, if specific conditions are not specified, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially.

[0049] Example 1:

[0050] A method for preparing a molecular sieve-loaded high-entropy alloy nanoparticle material comprises the following steps:

[0051] (1) Na2PdCl4, K2PtCl4, RhCl3·xH2O, H2IrCl6·xH2O, and RuCl3·xH2O were added to 3 mL of ethylene glycol to prepare a metal salt precursor solution, wherein the concentration of each metal salt was 0.011 mmol / mL. 0.5 g of polyvinylpyrrolidone and 0.05 g of L-ascorbic acid were then added to 7 mL of ethylene glycol to prepare a reaction solution.

[0052] (2) slowly adding the metal salt precursor solution obtained in step (1) to the reaction solution preheated to 180° C. at a dropwise rate of 0.05 mL / min through a syringe pump, and continuously stirring the reaction at 180° C. until all the metal salt precursor is added dropwise to the reaction solution, stopping the reaction, and obtaining a high entropy alloy nanoparticle dispersion;

[0053] (3) Adding acetone to the high entropy alloy nanoparticle dispersion obtained in step (2) at a volume ratio of 1:5, then centrifuging at a centrifugal speed of 8000 rpm for 30 minutes, removing the supernatant, and obtaining high entropy alloy nanoparticles. Figure 1 The HAADF-STEM image of the prepared high-entropy alloy nanoparticles shows that the prepared high-entropy alloy nanoparticles have a three-dimensional dendrite morphology. Figure 2The size distribution of high entropy alloy nanoparticles is about 11 nm. Figure 3 The composition of the high-entropy alloy nanoparticles (Pt, Pd, Ir, Ru, Rh) is statistically analyzed. The elements in the synthesized high-entropy alloy nanoparticles are uniformly distributed, with the atomic percentage of all elements around 20%.

[0054] (4) The high entropy alloy nanoparticles obtained in step (3) were mixed evenly with 80 mL of ethanol and 6 mL of ammonia water, 3.47 g of tetraethyl orthosilicate was added, and the mixture was stirred at room temperature for 8 h, and then rotary evaporated at 60 ° C to remove the solvent, and vacuum dried at 100 ° C overnight to obtain high entropy alloy @ silicon dioxide powder. Figure 4 This is a HADDF-STEM image of a high-entropy alloy@silica. High-entropy alloy nanoparticles are encapsulated by silica to form high-entropy alloy@silica microspheres, approximately 80 nm in size.

[0055] (5) The high entropy alloy @silica powder was mixed with 0.83 g of tetrapropylammonium hydroxide, ground, heated and dried to remove moisture, and the mixture was transferred to a high-pressure reactor. 400 μL of ultrapure water was added to the reactor, and the mixture was placed in an oven at 180°C for 3 days to crystallize. The mixture was then centrifuged at a centrifugal speed of 10,000 rpm for 30 minutes, the supernatant was removed, and the product was repeatedly washed 3 times with ultrapure water, dried and ground. The molecular sieve powder loaded with high entropy alloy nanoparticles was placed in an air atmosphere, first heated to 550°C at a heating rate of 5°C / min and maintained for 4 hours, then cooled to room temperature, and the high entropy alloy @MFI zeolite molecular sieve powder was collected. Figure 5 This is a HADDF-STEM image of a high-entropy alloy@MFI. The white bright spots in the image are high-entropy alloy nanoparticles. As can be seen from the image, the particles are evenly distributed.

[0056] Example 2:

[0057] A method for preparing a molecular sieve-loaded high-entropy alloy nanoparticle material comprises the following steps:

[0058] (1) PdCl4, PtCl4, RhCl3, IrCl4, and RuCl3 were first added to 5 mL of ethylene glycol to prepare a metal salt precursor solution, wherein the concentration of each metal salt was 0.011 mmol / mL. Then, 2 g of polyvinylpyrrolidone and 0.1 g of L-ascorbic acid were added to 9 mL of ethylene glycol to prepare a reaction solution;

[0059] (2) slowly adding the metal salt precursor solution obtained in step (1) into the preheated reaction solution through a syringe pump at a dropwise rate of 3 mL / min, and continuously stirring the reaction at 230° C. until all the metal salt precursor is added dropwise into the reaction solution, stopping the reaction, and obtaining a high entropy alloy nanoparticle dispersion;

[0060] (3) adding acetone to the high entropy alloy nanoparticle dispersion obtained in step (2) at a volume ratio of 1:10, then centrifuging at a centrifugal speed of 12000 rpm for 60 minutes, removing the supernatant, and obtaining high entropy alloy nanoparticles;

[0061] (4) 80 mL of ethanol and 6 mL of ammonia water were mixed evenly to obtain the high entropy alloy nanoparticles obtained in step (3), 3.5 g of tetraethyl orthosilicate was added, and the mixture was stirred at room temperature for 12 h, and then rotary evaporated at 80 ° C to remove the solvent, and vacuum dried at 100 ° C overnight to obtain high entropy alloy@silica powder;

[0062] (5) The high entropy alloy @silica powder obtained in step (4) was mixed with 0.9 g of tetrapropylammonium hydroxide, ground, heated and dried to remove moisture, and the mixture was transferred to a high-pressure reactor, and 1600 μL of ultrapure water was added to the reactor. The mixture was placed in a 120°C oven and allowed to stand for 5 days for crystallization, and then centrifuged at a centrifugal speed of 12000 rpm for 60 minutes. The supernatant was removed, and the product was repeatedly washed 3 times with ultrapure water, dried and ground. The molecular sieve powder loaded with high entropy alloy nanoparticles was placed in an air atmosphere, first heated to 550°C at a heating rate of 10°C / min, maintained for 4 hours, and then cooled to room temperature to collect and obtain high entropy alloy @MFI zeolite molecular sieve powder.

[0063] Example 3:

[0064] A method for preparing a molecular sieve-loaded high-entropy alloy nanoparticle material comprises the following steps:

[0065] (1) First, AuCl4, CuCl4, FeCl3, CoCl2, and NiCl2 were added to 1 mL of ethylene glycol to prepare a metal salt precursor solution, wherein the concentration of each metal salt was 0.011 mmol / mL. Then, 0.01 g of polyvinyl pyrrolidone and 0.01 g of L-ascorbic acid were added to 5 mL of ethylene glycol to prepare a reaction solution;

[0066] (2) slowly adding the metal salt precursor solution obtained in step (1) into the preheated reaction solution through a syringe pump at a dropwise rate of 0.005 mL / min, and continuously stirring the reaction at 150° C. until all the metal salt precursor is added dropwise into the reaction solution, stopping the reaction, and obtaining a high entropy alloy nanoparticle dispersion;

[0067] (3) adding acetone to the high entropy alloy nanoparticle dispersion obtained in step (2) at a volume ratio of 1:5, then centrifuging at a centrifugal speed of 8000 rpm for 30 minutes, removing the supernatant, and obtaining high entropy alloy nanoparticles;

[0068] (4) The high entropy alloy nanoparticles obtained in step (3) were mixed evenly with 80 mL of ethanol and 6 mL of ammonia water, 3.4 g of tetraethyl orthosilicate was added, and the mixture was stirred at room temperature for 6 h, and then rotary evaporated at 60 ° C to remove the solvent, and vacuum dried at 80 ° C overnight to obtain high entropy alloy@silica powder;

[0069] (5) The high entropy alloy @silica powder obtained in step (4) was mixed with 0.8 g of tetrapropylammonium hydroxide, ground, heated and dried to remove moisture, and the mixture was transferred to a high-pressure reactor, and 200 μL of ultrapure water was added to the reactor. The mixture was placed in a 200°C oven and allowed to stand for 1 day for crystallization, and then centrifuged at a centrifugal speed of 8000 rpm for 30 minutes. The supernatant was removed, and the product was repeatedly washed 3 times with ultrapure water, dried and ground. The molecular sieve powder loaded with high entropy alloy nanoparticles was placed in an air atmosphere, first heated to 550°C at a heating rate of 2°C / min, maintained for 4 hours, and then cooled to room temperature to collect and obtain high entropy alloy @MFI zeolite molecular sieve powder.

[0070] Example 4:

[0071] A method for preparing a molecular sieve-loaded high-entropy alloy nanoparticle material comprises the following steps:

[0072] (1) Na2PdCl4, K2PtCl4, Na2AuCl4·2H2O, CuCl2·2H2O, and NiCl2·xH2O were added to 3 mL of ethylene glycol to prepare a metal salt precursor solution, wherein the concentration of each metal salt was 0.011 mmol / mL. 0.05 g of polyvinylpyrrolidone and 0.05 g of L-ascorbic acid were then added to 7 mL of ethylene glycol to prepare a reaction solution.

[0073] (2) slowly adding the metal salt precursor solution obtained in step (1) into the preheated reaction solution through a syringe pump at a dropwise rate of 0.5 mL / min, and continuously stirring the reaction at 180° C. until all the metal salt precursor is added dropwise into the reaction solution, stopping the reaction, and obtaining a high entropy alloy nanoparticle dispersion;

[0074] (3) adding acetone to the high entropy alloy nanoparticle dispersion obtained in step (2) in a volume ratio of 1:5, then centrifuging at a centrifugal speed of 8000 rpm for 30 minutes, removing the supernatant, and obtaining high entropy alloy nanoparticles;

[0075] (4) The high entropy alloy nanoparticles obtained in step (3) were mixed evenly with 80 mL of ethanol and 6 mL of ammonia water, 3.4 g of tetraethyl orthosilicate was added, and the mixture was stirred at room temperature for 8 h, and then rotary evaporated at 60 ° C to remove the solvent, and vacuum dried at 100 ° C overnight to obtain high entropy alloy@silica powder;

[0076] (5) The high entropy alloy @silica powder obtained in step (4) was mixed with 0.83 g of tetrapropylammonium hydroxide, ground, heated and dried to remove moisture, and the mixture was transferred to a high-pressure reactor, and 400 μL of ultrapure water was added to the reactor. The mixture was placed in an oven at 180°C for 3 days to crystallize, and then centrifuged at a centrifugal speed of 10,000 rpm for 30 minutes. The supernatant was removed, and the product was repeatedly washed 3 times with ultrapure water, dried and ground. The molecular sieve powder loaded with high entropy alloy nanoparticles was placed in an air atmosphere, first heated to 550°C at a heating rate of 5°C / min, maintained for 4 hours, and then cooled to room temperature to collect and obtain high entropy alloy @MFI zeolite molecular sieve powder.

[0077] Example 5:

[0078] A method for preparing a molecular sieve-loaded high-entropy alloy nanoparticle material comprises the following steps:

[0079] (1) Na2PdCl4, K2PtCl4, RhCl3·xH2O, HAuCl4·3H2O, H2IrCl6·xH2O, RuCl3·xH2O, CuCl2·2H2O, NiCl2·6H2O, FeCl2·xH2O, and CoCl2·xH2O were first added to 3 mL of ethylene glycol to prepare a metal salt precursor solution, wherein the concentration of each metal salt was 0.011 mmol / mL. 0.05 g of polyvinylpyrrolidone and 0.05 g of L-ascorbic acid were then added to 7 mL of ethylene glycol to prepare a reaction solution.

[0080] (2) slowly adding the metal salt precursor solution obtained in step (1) to the preheated reaction solution through a syringe pump at a dropwise rate of 0.05 mL / min, and continuously stirring the reaction at 200° C. until all the metal salt precursor is added dropwise to the reaction solution, stopping the reaction, and obtaining a high entropy alloy nanoparticle dispersion;

[0081] (3) adding acetone to the high entropy alloy nanoparticle dispersion obtained in step (2) at a volume ratio of 1:6, then centrifuging at a centrifugal speed of 8000 rpm for 30 minutes, removing the supernatant, and obtaining high entropy alloy nanoparticles;

[0082] (4) The high entropy alloy nanoparticles obtained in step (3) were mixed evenly with 80 mL of ethanol and 6 mL of ammonia water, 3.47 g of tetraethyl orthosilicate was added, and the mixture was stirred at room temperature for 7 h, and then rotary evaporated at 80 ° C to remove the solvent, and vacuum dried at 100 ° C overnight to obtain high entropy alloy@silica powder;

[0083] (5) The high entropy alloy @silica powder obtained in step (4) was mixed with 0.8 g of tetrapropylammonium hydroxide, ground, heated and dried to remove moisture, and the mixture was transferred to a high-pressure reactor, and 1600 μL of ultrapure water was added to the reactor. The mixture was placed in a 200°C oven and allowed to stand for 5 days for crystallization, and then centrifuged at a centrifugal speed of 8000 rpm for 30 minutes. The supernatant was removed, and the product was repeatedly washed 3 times with ultrapure water, dried and ground. The molecular sieve powder loaded with high entropy alloy nanoparticles was placed in an air atmosphere, first heated to 550°C at a heating rate of 5°C / min, maintained for 4 hours, and then cooled to room temperature to collect and obtain high entropy alloy @MFI zeolite molecular sieve powder.

[0084] Comparative Example 1:

[0085] A method for preparing a molecular sieve-loaded high-entropy alloy nanoparticle material comprises the following steps:

[0086] (1) First, Na2PdCl4, K2PtCl4, RhCl3·xH2O, H2IrCl6·xH2O, and RuCl3·xH2O were added to 3 mL of ethylene glycol to prepare a metal salt precursor solution, wherein the concentration of each metal salt was 0.011 mmol / mL. Then, 0.5 g of polyvinylpyrrolidone and 0.05 g of L-ascorbic acid were added to 7 mL of ethylene glycol to prepare a reaction solution;

[0087] (2) slowly adding the metal salt precursor solution obtained in step (1) into the preheated reaction solution through a syringe pump at a dropwise rate of 0.05 mL / min, and continuously stirring the reaction at 180° C. until all the metal salt precursor is added dropwise into the reaction solution, stopping the reaction, and obtaining a high entropy alloy nanoparticle dispersion;

[0088] (3) adding acetone to the high entropy alloy nanoparticle dispersion obtained in step (2) at a volume ratio of 1:5, then centrifuging at a centrifugal speed of 8000 rpm for 30 minutes, removing the supernatant, and obtaining high entropy alloy nanoparticles;

[0089] (4) 80 mL of ethanol and 6 mL of ammonia water were mixed evenly, 3.47 g of tetraethyl orthosilicate was added, and the mixture was stirred at room temperature for 8 h. The solvent was then removed by rotary evaporation at 60 ° C. and vacuum dried at 100 ° C overnight to obtain silica powder;

[0090] (5) The silica powder is mixed with the high entropy alloy nanoparticles obtained in step (3) and 0.83 g of tetrapropylammonium hydroxide, ground, heated and dried to remove moisture, and the mixture is transferred to a high-pressure reactor, and 400 μL of ultrapure water is added to the reactor, and the mixture is placed in a 180°C oven for 3 days to crystallize, and then centrifuged at a centrifugal speed of 10,000 rpm for 30 minutes, the supernatant is removed, and the product is repeatedly washed 3 times with ultrapure water, dried and ground, and the molecular sieve powder loaded with metal nanoparticles is placed in an air atmosphere, first heated to 550°C at a heating rate of 5°C / min and maintained for 4 hours, and then cooled to room temperature, and the high entropy alloy / MFI zeolite molecular sieve powder is collected. Figure 6 This is a HADDF-STEM image of a high-entropy alloy / MFI. The white bright spots in the image are high-entropy alloy nanoparticles. As can be seen from the image, the particles are unevenly distributed, severely agglomerated, and distributed outside the MFI zeolite molecular sieve.

[0091] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing molecular sieve-loaded high-entropy alloy nanoparticle material, characterized in that: The following steps are involved: (1) adding a metal salt precursor solution to a mixed polyol solution of polyvinyl pyrrolidone and L-ascorbic acid to react and prepare a high entropy alloy nanoparticle dispersion; (2) adding acetone to the dispersion obtained in step (1), centrifuging, and obtaining high entropy alloy nanoparticles; (3) uniformly mixing the high entropy alloy nanoparticles obtained in step (2) with a solvent and an alkaline solution, adding tetraethyl orthosilicate, stirring, and drying to obtain a high entropy alloy@silica powder; (4) The high entropy alloy@silica powder obtained in step (3) is first mixed with tetrapropylammonium hydroxide, ground, heated and dried, and then ultrapure water is added, allowed to stand for crystallization, and finally centrifuged and the solid product is calcined to obtain; Wherein, in said step (1), the concentration of each metal salt in the metal salt precursor solution is 0.01-0.015 mmol / mL, and the solvent is ethylene glycol; The polyvinyl pyrrolidone and L-ascorbic acid mixed polyol solution has a concentration of 0.001-0.4 g / mL of polyvinyl pyrrolidone, a concentration of 0.001-0.01 g / mL of L-ascorbic acid, and ethylene glycol as the solvent; The metal salt precursor solution is added to the reaction solution by dropwise injection at an injection rate of 0.005-3 mL / min. The reaction solution temperature is preheated to 150-230°C before addition. When all the metal salt precursor solution is dropwise injected into the reaction solution, the reaction is stopped.

2. The method for preparing the molecular sieve-loaded high-entropy alloy nanoparticle material according to claim 1, characterized in that: The metal salt in step (1) is at least five of palladium inorganic salts, platinum inorganic salts, rhodium inorganic salts, ruthenium inorganic salts, iridium inorganic salts, gold inorganic salts, copper inorganic salts, iron inorganic salts, cobalt inorganic salts and nickel inorganic salts.

3. The method for preparing the molecular sieve-loaded high-entropy alloy nanoparticle material according to claim 2, characterized in that: The palladium inorganic salt is any one of PdCl2, PdCl4, Na2PdCl4, Na2PdCl6, K2PdCl4 and K2PdCl6; The platinum inorganic salt is any one of PtCl2, PtCl4, Na2PtCl6, Na2PtCl6·6H2O, K2PtCl4 and K2PtCl6; The rhodium inorganic salt is any one of RhCl3, RhCl3·3H2O and K3RhCl6; The ruthenium inorganic salt is one of RuCl3, RuCl3·3H2O, K2RuCl6 and K3RuCl6; The iridium inorganic salt is any one of IrCl3, IrCl4, IrCl3·3H2O, Na2IrCl6·6H2O and K3IrCl6; The gold inorganic salt is any one of AuCl, NaAuCl4·2H2O and HAuCl4·3H2O; The copper inorganic salt is any one of CuCl, CuCl2, CuCl2·H2O and CuCl2·2H2O; The iron inorganic salt is any one of FeCl2, FeCl3, FeCl2·2H2O, FeCl2·4H2O and FeCl3·6H2O; The cobalt inorganic salt is any one of CoCl2 and CoCl2·6H2O; The nickel inorganic salt is any one of NiCl2 and NiCl2·6H2O.

4. The method for preparing molecular sieve-loaded high-entropy alloy nanoparticle material according to claim 1, characterized in that: The molecular weight of polyvinyl pyrrolidone in step (1) is 2500-58000.

5. The method for preparing molecular sieve-loaded high-entropy alloy nanoparticle material according to claim 1, characterized in that: In step (2), the volume ratio of the dispersion to acetone is 1 / 5-1 / 10; the centrifugal speed is 8000-12000 rpm, and the time is 30-60 min.

6. The method for preparing molecular sieve-loaded high-entropy alloy nanoparticle material according to claim 1, characterized in that: In step (3), the mass volume ratio of tetraethyl orthosilicate, solvent and alkaline solution is 3-4 g:50-100 mL:5-7 mL, the solvent is ethanol, and the alkaline solution is ammonia water; the stirring time is 6-12 h; the drying temperature is 80-100° C., and the drying time is 5-24 h.

7. The method for preparing molecular sieve-loaded high-entropy alloy nanoparticle material according to claim 1, characterized in that: The mass ratio of tetrapropylammonium hydroxide in step (4) to tetraethyl orthosilicate in step (3) is 0.5-1:3-4; the mass volume ratio of tetrapropylammonium hydroxide to ultrapure water is 0.5-1 g:200-1600 μL; the temperature of the static crystallization is 120-200°C, and the time is 1-5 d; the speed of the centrifuge is 8000-12000 rpm, and the time is 30-60 min; the calcination conditions are: in an air atmosphere, first heating to 500-600°C at a heating rate of 2-10°C / min, then keeping warm for 4-5 h, and then cooling to room temperature.

8. A molecular sieve-loaded high entropy alloy nanoparticle material, characterized in that: The method is prepared according to any one of claims 1 to 7.

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