A Pt-encapsulated Beta zeolite molecular sieve, its preparation method and application

Abstract

This invention discloses a Pt-encapsulated Beta zeolite molecular sieve, its preparation method, and its applications, relating to the field of catalyst preparation technology. A metal precursor formed by 3-mercaptopropyltrimethoxysilane and platinum is added to a mixed solution of water and acid, followed by the slow addition of a silicon source. The mixture is heated and stirred to form a gel. Water is added repeatedly to form a sol-gel process several times, resulting in a final gel. A template agent and an aluminum source are then added, dissolved in water, and aged at room temperature for a period of time. The gel is then transferred to a hydrothermal reactor for crystallization to obtain the product. After filtration, washing, drying, and grinding, a zeolite powder sample is obtained. The sample is calcined in air to remove the template agent, followed by reduction in a hydrogen-nitrogen mixed atmosphere to obtain the Pt-encapsulated Beta zeolite molecular sieve. This product exhibits high catalytic efficiency, high stability, and long lifetime as a catalyst in the oxidation of formaldehyde and the N-alkylation of alcohols and amines.

Description

Technical Field

[0001] This technology relates to the field of catalyst preparation technology, specifically to the preparation method of synthesizing Beta zeolite encapsulated with the noble metal Pt and its application in formaldehyde oxidation and N-alkylation reactions. Background Technology

[0002] Zeolites are crystalline aluminosilicates containing channels of ordered molecular size. Generally, the pores of zeolites can regulate molecular diffusion, leading to differential molecular transport and ultimately shape-selective catalysis. From their initial discovery as natural minerals to their later large-scale commercial production, zeolites have played an indispensable role in various fields such as petroleum refining and chemical engineering.

[0003] Ruthenium, rhodium, palladium, iridium, platinum, gold, and silver are considered the most effective catalysts for industrial catalysis, energy conversion, and environmental remediation. Considering practical applications and structural stability, porous zeolite materials, as supports for nano-metal dispersions, can enhance interactions and reduce the amount of precious metals used, thereby lowering catalyst costs. They have been used in the synthesis of supported precious metal catalysts. Their advantages lie in the strong interaction between the nano-metals and the zeolite support, which prevents metal particle aggregation. By constructing stable and uniformly dispersed metal clusters, high catalytic activity and low precious metal consumption are achieved, resulting in high contact and shape-selective catalytic capabilities.

[0004] Zeolite-encapsulated noble metal materials exhibit unique catalytic properties, effectively addressing the shortcomings of catalysts supported on metal nanoparticles. In this type of structure, zeolite molecular sieves and noble metal nanoparticles possess a unique synergistic effect. For example, the rigid zeolite framework can anchor noble metal nanoparticles, improving their resistance to sintering; the zeolite channels possess shape selectivity, thereby regulating catalytic selectivity, and the channels can also enrich reactants to control local concentrations. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the technical problem this invention aims to solve is to provide a method for preparing Pt-encapsulated Beta zeolite molecular sieves. Another technical problem this invention aims to solve is to provide a product of Pt-encapsulated Beta zeolite molecular sieves. Finally, the technical problem this invention seeks to solve is to provide specific applications of the said Pt-encapsulated Beta zeolite molecular sieve.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing Pt-encapsulated Beta zeolite molecular sieves, comprising the following steps:

[0008] (1) The metal precursor formed by organosilane and platinum source is added to a mixed solution of water and acid, and then the silicon source is slowly added. The mixture is heated and stirred to form a gel. Water is added repeatedly to form a sol-gel process several times. After cooling to room temperature, the final gel is formed.

[0009] (2) Add the template agent and aluminum source to the gel obtained in step (1), dissolve them in water, and then stir and age them at room temperature for a period of time.

[0010] (3) The aged gel was transferred to a hydrothermal reactor for crystallization to obtain the product, and then a solid product was obtained by filtration, washing, drying and grinding.

[0011] (4) The solid product is calcined in air to remove the template agent, and then reduced in a hydrogen-nitrogen mixed atmosphere to obtain Pt-encapsulated Beta zeolite molecular sieve.

[0012] Preferably, the organosilane in step (1) is one or more of mercaptopropylmethoxysilane, aminopropylmethoxysilane, and chloropropylmethoxysilane; the platinum source is one or more of sodium tetrachloroplatinate, potassium sodium tetrachloroplatinate, and sodium hexachloroplatinate; and the silicon source is one or more of tetraethyl orthosilicate, silica, silica sol, and silicic acid.

[0013] Preferably, the temperature required for heating and stirring to form a gel in step (1) is 80-95°C.

[0014] Preferably, the molar ratio of the gel finally formed in step (1) is: SiO2∶Al2O3∶TEAOH∶H2O∶Pt∶MPTS=1∶0.06-0.12∶0.35∶17.1∶0.00034-0.0052∶0.0048-0.0728.

[0015] Preferably, the number of times mentioned in step (1) is two or more.

[0016] Preferably, the template agent in step (2) is a quaternary ammonium salt, such as tetraethylammonium hydroxide, tetramethylammonium hydroxide, tetrapropylammonium hydroxide, or tetrabutylammonium hydroxide.

[0017] Preferably, the stirring and aging process at room temperature in step (2) specifically refers to 24 hours or more.

[0018] Preferably, the crystallization conditions in step (3) are: 120-160℃, 10-14 days.

[0019] Preferably, the specific conditions for calcination to remove the template agent in step (4) are: 450-600℃, 4-6h; and the specific conditions for reduction in a hydrogen-nitrogen mixed atmosphere are: 200-400℃, 2-6h.

[0020] The product prepared by any of the methods described above.

[0021] The product is used as a catalyst in the formaldehyde oxidation reaction.

[0022] The product is used as a catalyst in the N-alkylation reactions of alcohols and amines.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] This invention provides a method for preparing Pt-encapsulated Beta zeolite molecular sieves. This method ensures that platinum nanoparticles, a noble metal nanocatalyst, are uniformly dispersed within the zeolite molecular sieve with strong interactions, exhibiting good structural stability and a wide platinum metal coverage area. When used as a catalyst in the oxidation of formaldehyde and the nitrogen alkylation of alcohols and amines, this Pt-encapsulated Beta zeolite molecular sieve demonstrates high catalytic efficiency, high Pt metal stability, long catalyst lifetime, and high Pt atom utilization, showing promising prospects for industrial applications. Attached Figure Description

[0025] Figure 1 XRD patterns of Pt@Beta and control sample Beta, and Pt / Beta;

[0026] Figure 2 SEM images of Pt@Beta and the control sample Beta, and Pt / Beta;

[0027] Figure 3 Nitrogen adsorption-desorption curves and pore size distribution diagrams for Pt@Beta and control sample Beta;

[0028] Figure 4 XRD patterns for Pt@Beta-16.8, Pt@Beta-6.3, 0.1% Pt@Beta and 2% Pt@Beta;

[0029] Figure 5 The graphs show the HCHO oxidation performance of Pt@Beta and control samples Beta, Pt / Beta, and Pt-Beta under different space velocity conditions. Detailed Implementation

[0030] To facilitate the explanation of the technical solution of this application, some concepts involved in this application will be explained first below.

[0031] Example 1

[0032] 0.03 g of sodium tetrachloroplatinate and 0.15 g of (3-mercaptopropyl)trimethoxysilane were mixed and added to a solution of 15.463 g of water and 0.4 mL of concentrated hydrochloric acid. Then, 10.577 mL of tetraethyl orthosilicate was slowly added. The mixture was stirred at 90 °C for 5 h to hydrolyze the silicon source. During the stirring process, when a gel formed, an appropriate amount of water was added to the beaker to dissolve it. Stirring continued to form a gel, and a small amount of water was added again to dissolve it. This sol-gel process was repeated several times. The final gel was cooled to room temperature and transferred to a glass beaker.

[0033] Add 7.365 mL of tetraethylammonium hydroxide and 0.512 g of sodium aluminate, and add an appropriate amount of deionized water and mix well. The resulting gel was further aged at room temperature for 24 h with stirring. The pH of the mixed solution was approximately 11.5, as measured by pH paper. The final molar ratio of the gel was: SiO2∶Al2O3∶TEAOH∶H2O∶Pt∶MPTS=1∶0.06∶0.35∶17.1∶0.00068∶0.00952. After aging, the gel was transferred to a stainless steel hydrothermal reactor with a polytetrafluoroethylene liner and statically hydrothermally crystallized at 140 °C for 14 days. After crystallization, the solid was separated by filtration, washed with deionized water until neutral, dried overnight at 100 °C, ground into powder, and then calcined at 550 °C for 5 h in air to remove the template agent. Finally, it was reduced at 240 °C for 4 h in a 10% H2 / 90% N2 atmosphere to obtain the final sample, denoted as Pt@Beta.

[0034] Example 2

[0035] 0.03 g of sodium tetrachloroplatinate and 0.15 g of (3-mercaptopropyl)trimethoxysilane were mixed and added to a solution of 15.463 g of water and 0.4 mL of concentrated hydrochloric acid. Then, 10.577 mL of tetraethyl orthosilicate was slowly added. The mixture was stirred at 90 °C for 5 h to hydrolyze the silicon source. During the stirring process, when a gel formed, an appropriate amount of water was added to the beaker to dissolve it. Stirring continued to form a gel, and a small amount of water was added again to dissolve it. This sol-gel process was repeated several times. The final gel was cooled to room temperature and transferred to a glass beaker.

[0036] Add 7.365 mL of tetraethylammonium hydroxide and 0.256 g of sodium aluminate, and add an appropriate amount of deionized water and mix well. The resulting gel was further aged at room temperature for 24 h with stirring. The pH of the mixed solution was approximately 11.5, as measured by pH paper. The final molar ratio of the gel was: SiO2∶Al2O3∶TEAOH∶H2O∶Pt∶MPTS=1∶0.12∶0.35∶17.1∶0.00068∶0.00952. After aging, the gel was transferred to a stainless steel hydrothermal reactor with a polytetrafluoroethylene liner and statically hydrothermally crystallized at 140 °C for 14 days. After crystallization, the solid was separated by filtration, washed with deionized water until neutral, dried overnight at 100 °C, ground into powder, and then calcined at 550 °C for 5 h in air to remove the template agent. Finally, it was reduced at 240 °C for 4 h in a 10% H2 / 90% N2 atmosphere to obtain the final sample, denoted as Pt@Beta-16.8.

[0037] Example 3

[0038] 0.03 g of sodium tetrachloroplatinate and 0.15 g of (3-mercaptopropyl)trimethoxysilane were mixed and added to a solution of 15.463 g of water and 0.4 mL of concentrated hydrochloric acid. Then, 10.577 mL of tetraethyl orthosilicate was slowly added. The mixture was stirred at 90 °C for 5 h to hydrolyze the silicon source. During the stirring process, when a gel formed, an appropriate amount of water was added to the beaker to dissolve it. Stirring continued to form a gel, and a small amount of water was added again to dissolve it. This sol-gel process was repeated several times. The final gel was cooled to room temperature and transferred to a glass beaker.

[0039] Add 7.365 mL of tetraethylammonium hydroxide and 0.256 g of sodium aluminate, and add an appropriate amount of deionized water and mix well. The resulting gel was further aged at room temperature for 24 h with stirring. The pH of the mixed solution was approximately 11.5, as measured by pH paper. The final molar ratio of the gel was: SiO2∶Al2O3∶TEAOH∶H2O∶Pt∶MPTS=1∶0.08∶0.35∶17.1∶0.00068∶0.00952. After aging, the gel was transferred to a stainless steel hydrothermal reactor with a polytetrafluoroethylene liner and statically hydrothermally crystallized at 140 °C for 14 days. After crystallization, the solid was separated by filtration, washed with deionized water until neutral, dried overnight at 100 °C, ground into powder, and then calcined at 550 °C for 5 h in air to remove the template agent. Finally, it was reduced at 240 °C for 4 h in a 10% H2 / 90% N2 atmosphere to obtain the final sample, denoted as Pt@Beta-6.3.

[0040] Example 4

[0041] 0.3 g of sodium tetrachloroplatinate and 1.5 g of (3-mercaptopropyl)trimethoxysilane were mixed and added to a solution of 15.463 g of water and 0.4 mL of concentrated hydrochloric acid. Then, 10.577 mL of tetraethyl orthosilicate was slowly added. The mixture was stirred at 90 °C for 5 h to hydrolyze the silicon source. During the stirring process, when a gel formed, an appropriate amount of water was added to the beaker to dissolve it. Stirring continued to form a gel, and a small amount of water was added again to dissolve it. This sol-gel process was repeated several times. The final gel was cooled to room temperature and transferred to a glass beaker.

[0042] Add 7.365 mL of tetraethylammonium hydroxide and 0.256 g of sodium aluminate, and add an appropriate amount of deionized water and mix well. The resulting gel was further aged at room temperature for 24 h with stirring. The pH of the mixed solution was approximately 11.5, as measured by pH paper. The final molar ratio of the gel was: SiO2∶Al2O3∶TEAOH∶H2O∶Pt∶MPTS=1∶0.06∶0.35∶17.1∶0.00068∶0.0952. After aging, the gel was transferred to a stainless steel hydrothermal reactor with a polytetrafluoroethylene liner and statically hydrothermally crystallized at 140 °C for 14 days. After crystallization, the solid was separated by filtration, washed with deionized water until neutral, dried overnight at 100 °C, ground into powder, and then calcined at 550 °C for 5 h in air to remove the template agent. It was then reduced at 240 °C for 4 h in a 10% H2 / 90% N2 atmosphere to obtain the final sample, denoted as 2% Pt@Beta.

[0043] Example 5

[0044] 0.015 g of sodium tetrachloroplatinate and 0.075 g of (3-mercaptopropyl)trimethoxysilane were mixed and added to a solution of 15.463 g of water and 0.4 mL of concentrated hydrochloric acid. Then, 10.577 mL of tetraethyl orthosilicate was slowly added. The mixture was stirred at 90 °C for 5 h to hydrolyze the silicon source. During the stirring process, when a gel formed, a suitable amount of water was added to the beaker to dissolve it. Stirring continued to form a gel, and a small amount of water was added again to dissolve it. This sol-gel process was repeated several times. The final gel was cooled to room temperature and transferred to a glass beaker.

[0045] Add 7.365 mL of tetraethylammonium hydroxide and 0.256 g of sodium aluminate, and add an appropriate amount of deionized water and mix well. The resulting gel was further aged at room temperature for 24 h with stirring. The pH of the mixed solution was approximately 11.5, as measured by pH paper. The final molar ratio of the gel was: SiO2∶Al2O3∶TEAOH∶H2O∶Pt∶MPTS=1∶0.06∶0.35∶17.1∶0.00034∶0.0048. After aging, the gel was transferred to a stainless steel hydrothermal reactor with a polytetrafluoroethylene liner and statically hydrothermally crystallized at 140 °C for 14 days. After crystallization, the solid was separated by filtration, washed with deionized water until neutral, dried overnight at 100 °C, ground into powder, and then calcined at 550 °C for 5 h in air to remove the template agent. It was then reduced at 240 °C for 4 h in a 10% H2 / 90% N2 atmosphere to obtain the final sample, denoted as 0.1% Pt@Beta.

[0046] Comparative Example 1

[0047] Mix 15.463g of water, 0.4g of concentrated hydrochloric acid, and 10.577g of tetraethyl orthosilicate. Stir the mixture at 90°C for 5 hours to hydrolyze the silicon source. When a gel forms during stirring, add an appropriate amount of water to the beaker to dissolve it. Continue stirring to form a gel, and add a small amount of water again to dissolve it. Cool the final gel to room temperature and transfer it to a glass beaker.

[0048] Add 7.365 mL of tetraethylammonium hydroxide and 0.512 g of sodium aluminate, and add an appropriate amount of deionized water and stir until homogeneous. The resulting gel was further aged at room temperature for 24 h, and the pH of the mixed solution was approximately 11.5 as measured by pH paper. The final molar ratio of the gel was: SiO2∶Al2O3∶TEAOH∶H2O=1∶0.06∶0.35∶17.1. After aging, the gel was transferred to a stainless steel hydrothermal reactor with a polytetrafluoroethylene liner and statically hydrothermally crystallized at 140 °C for 14 days. After crystallization, the solid was separated by filtration, the filter cake was washed with deionized water until neutral, dried overnight at 100 °C, ground into powder, and then calcined at 550 °C for 5 h in air to remove the template agent, yielding the final sample, denoted as Beta.

[0049] Comparative Example 2

[0050] Comparative Example 1's Beta was mixed with an aqueous solution of Na₂PtCl₄. The mixture was first stirred at 370 rpm for 30 min at room temperature, then stirred in an 80°C water bath until the water was completely evaporated. The resulting solid powder was then calcined at 550°C for 5 h in air, followed by reduction at 240°C for 4 h in a 10% H₂ / 90% N₂ atmosphere. The final sample was denoted as Pt / Beta.

[0051] Comparative Example 3

[0052] 0.03 g of sodium tetrachloroplatinate and 0.15 g of (3-mercaptopropyl)trimethoxysilane were mixed and added to a mixture of 15.463 g of water and 0.4 mL of concentrated hydrochloric acid. Then, 10.577 mL of tetraethyl orthosilicate was slowly added. The mixture was stirred at 90 °C for 5 h to hydrolyze the silicon source. The resulting gel was then cooled to room temperature and transferred to a glass beaker.

[0053] Add 7.365 mL of tetraethylammonium hydroxide and 0.512 g of sodium aluminate, and add an appropriate amount of deionized water and mix well. The resulting gel was further aged at room temperature for 24 h with stirring. The pH of the mixed solution was approximately 11.5, as measured by pH paper. The final molar ratio of the gel was: SiO2∶Al2O3∶TEAOH∶H2O∶Pt∶MPTS=1∶0.06∶0.35∶17.1∶0.00068∶0.00952. After aging, the gel was transferred to a stainless steel hydrothermal reactor with a polytetrafluoroethylene liner and statically hydrothermally crystallized at 140 °C for 14 days. After crystallization, the solid was separated by filtration, washed with deionized water until neutral, dried overnight at 100 °C, ground into powder, and then calcined at 550 °C for 5 h in air to remove the template agent. Finally, it was reduced at 240 °C for 4 h in a 10% H2 / 90% N2 atmosphere to obtain the final sample, denoted as Pt-Beta.

[0054] Example 6

[0055] The samples from Examples 1-3 and the comparative examples were subjected to structural characterization and related performance tests, and the results are as follows: Figure 1-4 As shown:

[0056] Figure 1 The images show the XRD patterns of the sample from Example 1 and the comparative sample. The peaks exhibited by these samples are typical structural diffraction peaks of BEA-type zeolites, indicating that the samples have good crystallinity and that the inclusion of the noble metal Pt did not reduce the crystallinity of the samples.

[0057] Figure 2 These are SEM images of the sample from Example 1 and the comparative sample. It can be seen that the synthesized sample is ellipsoidal and has a similar morphology.

[0058] Figure 3 The figures show the nitrogen adsorption-desorption curves and pore size distributions of the sample from Example 1 and the comparative sample. The samples exhibit typical mixed adsorption curves of types I and IV. The specific surface areas of Example 1 and Comparative Example 1 are similar, while the specific surface area of ​​Comparative Example 2 is smaller. This is because the metal portion of the comparative example blocked the pores due to the subsequent loading, resulting in a decrease in specific surface area.

[0059] Figure 4The XRD patterns are for Pt@Beta-16.8, Pt@Beta-6.3, 0.1% Pt@Beta, and 2% Pt@Beta. The samples from different embodiments all belong to the typical structural diffraction peaks of BEA-type zeolites.

[0060] Example 7

[0061] The samples from Example 1 and the comparative example were subjected to a catalytic formaldehyde oxidation reaction. The reaction equations are as follows:

[0062] HCHO + O2 → CO2 + H2O

[0063] The catalytic oxidation reaction of HCHO was carried out in a fixed-bed reactor under atmospheric pressure and constant room temperature (25°C) using a thermostat. In the reaction, 0.05 g of catalyst was mixed with 0.35 g of 40-60 mesh quartz sand and packed into a quartz tube with an inner diameter of 6 mm. The total flow rate of the mixed gas was controlled at 300 mL / min. - 1. A continuous oxidation reaction is carried out in a continuously fed gas system, with an HCHO concentration of 80 ppm, 20% O2, and balanced with N2. The relative humidity (RH) of the mixed gas system is controlled at 10%. Gaseous HCHO is generated by passing N2 through paraformaldehyde in a constant-temperature water bath, and the HCHO concentration at the inlet and outlet of the reaction tube is detected by a formaldehyde detector.

[0064] Table 1 shows the formaldehyde oxidation conversion activity, reaction rate, and TOF of Example 1 and the comparative example. Example 1 has the best activity.

[0065] Table 1: Summary of reaction rates and TOF of catalysts

[0066]

[0067] Figure 5 The values ​​for Beta, Pt / Beta, and Pt@Beta were measured over 50 hours at a concentration of 360,000 mL (g·h). -1 Oxidation performance of HCHO at space velocities and Pt@Beta at 180,000 and 720,000 mL (g·h) -1 HCHO oxidation performance at space velocity. (When space velocity is 360,000 mL (g·h)) -1 At that time, Pt 0.2 @Beta exhibits the highest conversion rate (95%). The space velocity was reduced to 180,000 mL (g·h). -1 At this level, HCHO showed 100% conversion, and maintained a high conversion rate of 100% during a 50-hour stability test. When the space velocity was increased to 720,000 mL (g×h)... -1 The conversion rate of HCHO exceeded 65% at a space velocity of 360,000 mL (g × h).-1 When testing the HCHO oxidation performance of Beta, Pt / Beta, and Pt-Beta, it was found that Beta had no catalytic oxidation activity, only adsorbing formaldehyde, and the conversion rate rapidly dropped to 0. Pt 0.2 The initial HCHO conversion rate of / Beta was 28%, but it decreased to 15% with increasing reaction time, which is much lower than that of Pt. 0.2 The catalytic activity of Pt-Beta was examined. The HCHO conversion rate of Pt-Beta was 45%, decreasing to 30% over time, significantly lower than that of Pt-Beta. 0.2 @Beta's catalytic activity.

[0068] Example 8

[0069] The sample prepared in Example 1 was used to catalyze the N-alkylation reaction of benzyl alcohol and aniline. The reaction equation is as follows:

[0070]

[0071] The reaction was carried out in a 10 mL reaction tube with 3 mmol of benzyl alcohol, 1 mmol of aniline, and 70 mg of catalyst. The reaction was carried out under solvent-free conditions at 160 °C for 2.5 h, with 1 bar of N2 as a protective gas. After the reaction was complete, 135 μL of dodecane was added as an internal standard, and the reaction solution was diluted to 5 mL with ethanol. The product was analyzed using an Agilent 8860 gas chromatograph. The remaining catalyst was filtered off, washed repeatedly with ethanol, and dried in a 100 °C oven. The recovered sample was used for the next cycle of experiments.

[0072] The N-alkylation reaction of benzyl alcohol and aniline was catalyzed using samples prepared in Example 1 and the comparative example. The conversion and yield are shown in Table 2 below.

[0073] Table 2: Comparison of the activities of different catalysts in the N-alkylation reaction of benzyl alcohol and aniline.

[0074]

[0075] The data in Table 2 show that the sample of Example 1 has the best reactivity. Therefore, further substrate expansion experiments were conducted on Example 1, and the results are shown in Table 3.

[0076] Table 3: Application of the Sample from Example 1 in N-alkylation Reactions of Different Substrates

[0077]

[0078]

[0079] As shown in Table 3 above, the sample of Example 1 exhibited excellent reactivity in the N-alkylation reactions of different alcohols and amines.

Claims

1. The application of a Pt-encapsulated Beta zeolite molecular sieve as a catalyst in the N-alkylation reactions of alcohols and amines, characterized in that, The substrates for the N-alkylation reaction are benzyl alcohol and 4-methylaniline, benzyl alcohol and 3-methylaniline, benzyl alcohol and 2-methylaniline, benzyl alcohol and 4-methoxyaniline, benzyl alcohol and 4-chloroaniline, 4-methylbenzyl alcohol and aniline, 2-methylbenzyl alcohol and aniline, 4-methoxybenzyl alcohol and aniline, and 4-chlorobenzyl alcohol and aniline. The preparation steps of the Pt-encapsulated Beta zeolite molecular sieve are as follows: (1) Add the metal precursor formed by mercaptopropyl methoxysilane and platinum source to a mixed solution of water and acid, then slowly add silicon source, heat and stir to form gel, then repeat the addition of water to form sol-gel process several times, and cool to room temperature to form final gel. (2) Add the template agent and aluminum source to the gel obtained in step (1), dissolve them in water, stir and age at room temperature for a period of time, and the molar ratio of the gel is: SiO2: Al2O3: TEAOH: H2O: Pt: MPTS = 1: 0.06-0.12:0.35: 17.1: 0.00034-0.0052: 0.0048-0.0728; (3) The aged gel is transferred to a hydrothermal reactor for crystallization to obtain the product, and then a solid product is obtained after filtration, washing, drying and grinding. (4) The solid product was calcined in air to remove the template agent, and then reduced in a hydrogen-nitrogen mixed atmosphere to obtain Pt-encapsulated Beta zeolite molecular sieve. The platinum source is one or more of sodium tetrachloroplatinate, potassium sodium tetrachloroplatinate, and sodium hexachloroplatinate; the silicon source is one or more of tetraethyl orthosilicate, silica, silica sol, and silicic acid; and the template agent is TEAOH.

2. The application according to claim 1, characterized in that, The temperature required for heating and stirring to form a gel in step (1) is 80-95 ℃.

3. The application according to claim 1, characterized in that, The crystallization conditions described in step (3) are: 120-160 ℃, 10-14 days.

4. The application according to claim 1, characterized in that, The specific conditions for calcining to remove the template agent in step (4) are: 450-600 ℃, 4-6 h; the specific conditions for reduction in a hydrogen-nitrogen mixed atmosphere are: 200-400 ℃, 2-6 h.

Images