Pt-containing EU-1 molecular sieve and preparation method thereof

Abstract

The invention relates to a Pt-containing EU-1 molecular sieve and a preparation method thereof, the EU-1 molecular sieve contains a Pt active component, and at least a part of the Pt active component is encapsulated in a crystal of the EU-1 molecular sieve. The Pt active component in the EU-1 molecular sieve containing Pt is encapsulated in the crystal, the particle size is small, agglomeration is avoided, and the crystallinity of the molecular sieve is high.

Description

Technical Field

[0001] The present disclosure relates to the field of preparation of silicon-alumina molecular sieves, and in particular, to a Pt-containing EU-1 molecular sieve and a preparation method thereof. Background Art

[0002] Zeolite molecular sieve is a functional material with unique structure and properties, which has been widely used in petrochemical, fine chemical, environmental protection and other fields.

[0003] The EUO molecular sieve has a one-dimensional pore network structure with a pore size of 0.41×0.57 nanometers. These one-dimensional pores also have side pockets with a depth of 0.81 nanometers and a diameter of 0.68×0.58 nanometers.

[0004] US4537754 discloses a EU-1 type molecular sieve and a method for synthesizing the same. The alkylated derivative of polymethylene α-ω-diamine ion or its precursor is used as a template, and a silicon source, an aluminum source, an alkali metal compound, a template and water are uniformly mixed and then hydrothermally crystallized to obtain the molecular sieve. The template precursor is a parent diamine and an alcohol or an alkyl halide. The synthesized EU-1 type molecular sieve has a SiO2 / Al2O3 molar ratio of 10-500.

[0005] Patent CN 109876852 A discloses a Pt-encapsulated ZSM-5 molecular sieve, which is synthesized using Pt-loaded nano-silica as a raw material.

[0006] EU-1 molecular sieves encapsulating Pt have not been reported. Since the conditions for synthesizing EU-1 molecular sieves are relatively harsh, Pt will automatically precipitate and agglomerate under the existing synthesis system, making it impossible to prepare EU-1 molecular sieves encapsulating Pt. Summary of the invention

[0007] The purpose of the present disclosure is to provide a Pt-containing EU-1 molecular sieve and a preparation method thereof.

[0008] In order to achieve the above objectives, the first aspect of the present disclosure provides a Pt-containing EU-1 molecular sieve, wherein the EU-1 molecular sieve contains a Pt active component, and at least part of the Pt active component is encapsulated inside the crystal of the EU-1 molecular sieve.

[0009] Optionally, based on the total weight of the Pt-containing EU-1 molecular sieve, the content of the Pt element is 0.03-2 wt %;

[0010] The particle size of the Pt active component is less than 3 nm.

[0011] Optionally, the Pt-containing EU-1 molecular sieve has a relative crystallinity of more than 90% and a pore volume of 0.2-0.4 cm 3 / g, specific surface area is 390-430m 2 / g, silicon-aluminum ratio is 20-300.

[0012] A second aspect of the present disclosure provides a method for preparing a Pt-containing EU-1 molecular sieve, the method comprising the following steps:

[0013] S1, contacting a first silicon source, a first aluminum source, a first alkali source, a template agent and water to perform a first hydrothermal crystallization reaction to obtain a directing agent;

[0014] S2, contacting a platinum source, a molecular sieve raw material and water for reaction, and subjecting the obtained solid product to a first heat treatment to obtain a first material;

[0015] S3. Contacting the first material, an optional second silicon source, an optional second aluminum source, a second alkali source, the directing agent and water, subjecting the obtained mixture to a second hydrothermal crystallization reaction, and then subjecting the solid product obtained by the second hydrothermal crystallization reaction to a second heat treatment.

[0016] Optionally, the first silicon source and the second silicon source are the same or different, and independently include one or more of amorphous aluminum silicate, aluminum silicate balls, amorphous silicon dioxide, silica sol, ethyl orthosilicate, propyl orthosilicate and butyl orthosilicate;

[0017] The first aluminum source and the second aluminum source are the same or different, and independently include one or more of amorphous aluminum silicate, silica-aluminum balls, sodium aluminate, aluminum sulfate, aluminum nitrate, alkoxy aluminum, aluminum oxide, aluminum sol, pseudo-boehmite and boehmite;

[0018] The first alkali source and the second alkali source are the same or different, and independently include one or more of NaOH, LiOH and KOH;

[0019] The platinum source includes tetraammineplatinum chloride;

[0020] The template agent includes one or more of dibenzyl dimethyl ammonium salt, alkylated polymethylene α-ω diammonium salt, a precursor of dibenzyl dimethyl ammonium salt and a precursor of alkylated polymethylene α-ω diammonium salt;

[0021] The molecular sieve raw material includes a molecular sieve with a pore size of 0.6 nm or more, preferably including one or more of X molecular sieve, Y molecular sieve, β molecular sieve and mercerized molecular sieve.

[0022] Optionally, in step S1, the molar ratio of the template, the first alkali source calculated as metal oxide, the first aluminum source calculated as Al2O3, water and the first silicon source calculated as SiO2 is (0.1-0.7): (0.05-0.3): (0.003-0.05): (10-100): 1;

[0023] In step S2, the weight ratio of the platinum source calculated as Pt element to the molecular sieve raw material is 1:(20-100), and the weight ratio of the total weight of the platinum source and the molecular sieve raw material to the water is 1:(1-20);

[0024] In step S3, in the mixture, the molar ratio of the alkali metal element calculated as metal oxide, the aluminum element calculated as Al2O3, water and the silicon element calculated as SiO2 is (0.1-0.3): (0.005-0.05): (10-100): 1;

[0025] The weight ratio of the directing agent to the silicon element in the mixture calculated as SiO2 is (0.5-5):1.

[0026] Optionally, in step S1, the conditions of the first hydrothermal crystallization reaction include: time of 10-30h, temperature of 90-130°C.

[0027] Optionally, in step S2, the contact reaction conditions include: time of 0.4-2h, temperature of 80-100°C;

[0028] The conditions of the first heat treatment include: time of 2-6 hours and temperature of 450-550°C.

[0029] Optionally, in step S3, the conditions of the second hydrothermal crystallization reaction include: time of 40-100 hours, temperature of 160-200° C.; preferably, time of 50-80 hours, temperature of 170-190° C.;

[0030] The conditions of the second heat treatment include: time of 2-12 hours and temperature of 500-600°C.

[0031] A third aspect of the present disclosure provides a Pt-containing EU-1 molecular sieve prepared by the method described in the second aspect of the present disclosure.

[0032] Through the above technical scheme, the present invention uses the molecular sieve that has undergone Pt ion exchange as a raw material to prepare the Pt-containing EU-1 molecular sieve, thereby avoiding the agglomeration of the Pt active component. The EU-1 molecular sieve in which the Pt active component is encapsulated inside the crystal is synthesized by hydrothermal crystallization through the crystal transformation method. The Pt active component does not agglomerate and the molecular sieve has a high degree of crystallinity.

[0033] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings:

[0035] Figure 1 This is the X-ray diffraction (XRD) pattern of the Pt-containing EU-1 molecular sieve A prepared in Example 1 of the present disclosure.

[0036] Figure 2 This is a spherical aberration electron microscope image of the Pt-containing EU-1 molecular sieve A prepared in Example 1 of the present disclosure.

[0037] Figure 3 This is a spherical aberration electron microscope image of the Pt-containing EU-1 molecular sieve B prepared in Example 2 of the present disclosure.

[0038] Figure 4 This is a spherical aberration electron microscope image of the Pt-containing EU-1 molecular sieve C prepared in Example 3 of the present disclosure.

[0039] Figure 5 This is a spherical aberration electron microscope image of the Pt-containing EU-1 molecular sieve D prepared in Example 4 of the present disclosure.

[0040] Figure 6 This is a spherical aberration electron microscope image of the Pt-containing EU-1 molecular sieve E prepared in Comparative Example 1 of the present disclosure. DETAILED DESCRIPTION

[0041] The specific implementation of the present disclosure is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.

[0042] In a first aspect, the present disclosure provides a Pt-containing EU-1 molecular sieve, wherein the EU-1 molecular sieve contains a Pt active component, and at least a portion of the Pt active component is encapsulated inside the crystal of the EU-1 molecular sieve.

[0043] In the present disclosure, "at least part of the Pt active components are encapsulated inside the crystals of the EU-1 molecular sieve" means that part or all of the Pt active components exist inside the crystals of the EU-1 molecular sieve, and preferably all of the Pt active components exist inside the crystals of the EU-1 molecular sieve.

[0044] According to one embodiment of the present disclosure, based on the total weight of the Pt-containing EU-1 molecular sieve, the content of the Pt element is 0.03-2% by weight, preferably 0.05-1.5% by weight.

[0045] According to one embodiment of the present disclosure, the relative crystallinity of the Pt-containing EU-1 molecular sieve is above 90%, preferably above 95%, and the calculation basis of the relative crystallinity is the EU-1 molecular sieve synthesized by the hydrothermal crystallization method using trimethyl hexammonium dibromide as a template in Chinese patent application CN99126910.1; it can be seen from the spherical aberration electron microscopy image that the particle size of the Pt active component is small and does not aggregate, and the particle size of the Pt active component is less than 3nm, preferably less than 2nm, and more preferably 0.5-1.5nm.

[0046] According to one embodiment of the present disclosure, the pore volume of the Pt-containing EU-1 molecular sieve is 0.2-0.4 cm 3 / g, specific surface area is 390-430m 2 / g.

[0047] According to one embodiment of the present disclosure, the silicon-aluminum ratio of the Pt-containing EU-1 molecular sieve is 20-300, preferably 25-100, wherein the silicon-aluminum ratio refers to the molar ratio of SiO2 and Al2O3 in the molecular sieve.

[0048] A second aspect of the present disclosure provides a method for preparing a Pt-containing EU-1 molecular sieve, the method comprising the following steps:

[0049] S1, contacting a first silicon source, a first aluminum source, a first alkali source, a template agent and water to perform a first hydrothermal crystallization reaction to obtain a directing agent;

[0050] S2, contacting a platinum source, a molecular sieve raw material and water for reaction, and subjecting the obtained solid product to a first heat treatment to obtain a first material;

[0051] S3. Contacting the first material, an optional second silicon source, an optional second aluminum source, a second alkali source, the directing agent and water, subjecting the obtained mixture to a second hydrothermal crystallization reaction, and then subjecting the solid product obtained by the second hydrothermal crystallization reaction to a second heat treatment.

[0052] In the present disclosure, the first material is a Pt ion-exchanged molecular sieve, which is subjected to a hydrothermal crystallization reaction by means of crystal transformation to prepare an EU-1 molecular sieve in which the Pt active component is encapsulated inside the crystal, and the Pt active component does not agglomerate and the molecular sieve has a high degree of crystallinity.

[0053] In the present disclosure, the first heat treatment and the second heat treatment are performed in a conventional manner in the art, for example, calcination.

[0054] According to one embodiment of the present disclosure, the first silicon source and the second silicon source are the same or different, and independently include one or more of amorphous aluminum silicate, silica aluminum balls, amorphous silicon dioxide, silica sol, ethyl orthosilicate, propyl orthosilicate and butyl orthosilicate; the first aluminum source and the second aluminum source are the same or different, and independently include one or more of amorphous aluminum silicate, silica aluminum balls, sodium aluminate, aluminum sulfate, aluminum nitrate, alkoxy aluminum, aluminum oxide, aluminum sol, pseudo-boehmite and boehmite; wherein sodium aluminate, amorphous aluminum silicate and silica aluminum balls can be used as both silicon sources and aluminum sources.

[0055] According to one embodiment of the present disclosure, the first alkali source and the second alkali source may be, for example, an inorganic base, preferably an alkali metal hydroxide; specifically, the first alkali source and the second alkali source are the same or different, and independently include one or more of NaOH, LiOH and KOH; the platinum source includes tetraammineplatinum chloride, but is not limited thereto.

[0056] According to one embodiment of the present disclosure, the template agent includes one or more of dibenzyl dimethyl ammonium salt, alkylated polymethylene α-ω diammonium salt, a precursor of dibenzyl dimethyl ammonium salt and a precursor of alkylated polymethylene α-ω diammonium salt; wherein the precursor is a compound that can synthesize dibenzyl dimethyl ammonium salt or alkylated polymethylene α-ω diammonium salt; the alkylated polymethylene α-ω diammonium salt is preferably alkyl dibromethylene diammonium, for example, trimethyl dibromethylene diamine It can also be a mixture of trimethylammonium and dibromide, which is reacted in situ to generate trimethyl dibromide diammonium.

[0057] According to one embodiment of the present disclosure, the molecular sieve raw material is a large-pore molecular sieve with a pore size of 0.6 nm or more, preferably including one or more of X molecular sieve, Y molecular sieve, β molecular sieve and mercerized molecular sieve. When the molecular sieve raw material includes more than two types, there is no specific limitation on their ratio.

[0058] According to one embodiment of the present disclosure, in step S1, the molar ratio of the template, the first alkali source calculated as metal oxide, the first aluminum source calculated as Al2O3, water and the first silicon source calculated as SiO2 is (0.1-0.7): (0.05-0.3): (0.003-0.05): (10-100): 1; for example, when the first alkali source is NaOH, the amount of the first alkali source is calculated as Na2O.

[0059] According to one embodiment of the present disclosure, in step S2, the weight ratio of the platinum source calculated as Pt element to the molecular sieve raw material is 1:(20-100), preferably 1:(22-80); the weight ratio of the total weight of the platinum source and the molecular sieve raw material to the water (i.e., the solid-liquid ratio) is 1:(1-20).

[0060] According to one embodiment of the present disclosure, in step S3, in the mixture, the molar ratio of alkali metal oxide, aluminum element calculated as Al2O3, water and silicon element calculated as SiO2 is (0.1-0.3): (0.005-0.05): (10-100): 1.

[0061] According to one embodiment of the present disclosure, in step S3, the weight ratio of the directing agent to the weight of silicon element in the mixture calculated as SiO2 is (0.5-5):1.

[0062] According to an embodiment of the present disclosure, in step S1, the conditions of the first hydrothermal crystallization reaction include: time of 10-30 hours, temperature of 90-130° C.; the first hydrothermal crystallization reaction is carried out under the autogenous pressure of the reactor.

[0063] According to one embodiment of the present disclosure, in step S2, the conditions of the contact reaction include: time of 0.5-2h, temperature of 80-100°C, and in order to fully proceed with the reaction, the contact reaction can be carried out in a water bath.

[0064] According to one embodiment of the present disclosure, step S2 also includes: solid-liquid separation of the mixed material obtained by the contact reaction, and then drying the obtained solid material, and then performing a first heat treatment; wherein the drying method and conditions are conventional in the art, for example, the temperature can be 110-120°C, and the time can be 2-12h; the solid-liquid separation method is conventional in the art, for example, it can be filtration.

[0065] According to an embodiment of the present disclosure, in step S2, the conditions of the first heat treatment include: time of 2-6 hours and temperature of 450-550°C.

[0066] According to an embodiment of the present disclosure, in step S3, the conditions of the second hydrothermal crystallization reaction include: time is 40-100h, temperature is 160-200°C; preferably, time is 50-80h, temperature is 170-190°C.

[0067] According to an embodiment of the present disclosure, in step S3, the conditions of the second heat treatment include: time of 2-12 hours and temperature of 500-600°C.

[0068] According to one embodiment of the present disclosure, step S3 may include: mixing a first material, an optional second silicon source, an optional second aluminum source, a second alkali source and water, and then mixing and contacting the obtained mixture with a directing agent, performing a second hydrothermal crystallization reaction, and performing a second heat treatment on the obtained solid product.

[0069] According to one embodiment of the present disclosure, step S3 also includes: solid-liquid separation of the mixed material obtained by the second hydrothermal crystallization reaction, and then washing and drying the obtained solid material, and then performing a second heat treatment; wherein the drying method and conditions are conventional in the art, for example, the temperature can be 110-120°C, and the time can be 2-12h; the solid-liquid separation method is conventional in the art, for example, it can be filtration; the washing method is conventional in the art.

[0070] A third aspect of the present disclosure provides a Pt-containing EU-1 molecular sieve prepared by the method described in the second aspect of the present disclosure.

[0071] The above-mentioned Pt-containing EU-1 molecular sieve has the same characteristics as the molecular sieve described in the first aspect of the present disclosure, and will not be described in detail here.

[0072] The present disclosure will be further illustrated by examples below, but the present disclosure is not limited thereby. The instruments and reagents used in the examples of the present disclosure are all commonly used instruments and reagents by those skilled in the art unless otherwise specified.

[0073] XRD test conditions and instrument model: The molecular sieve phase was determined using an X-ray diffractometer (XRD) from PANalytical, with a tube voltage of 40 kV, a tube current of 40 mA, a Cu target Kα ray, and a scanning range of 2θ=5-50°.

[0074] Test conditions and instrument model of spherical aberration electron microscope: Scanning transmission microscopy (STEM) was used to characterize the distribution position and particle size of Pt in the sample. The instrument used was JEOL JEL-ARM 200F. Before the sample was tested, a dispersion containing the molecular sieve sample was prepared by dispersing with ethanol, and then the dispersion was dropped on a copper mesh. After the ethanol evaporated, the sample was put into the instrument for testing.

[0075] Testing method for the content of Pt active components: The chemical composition and Pt content of the molecular sieve were determined using a 3013 X-ray fluorescence spectrometer (XRF) produced by Rigaku Corporation of Japan.

[0076] The test method of relative crystallinity: the ratio of the sum of the XRD diffraction peak intensities of the sample to the sum of the diffraction peak intensities of the standard sample*100%, the standard sample is 100%.

[0077] Particle size testing method: STEM.

[0078] Test methods and conditions for specific surface area and pore volume: The pore structure of the sample was characterized by nitrogen adsorption and desorption technology. The instrument used was Micromeritics ASAP 2420. The test conditions were: the sample was vacuum degassed at 350°C for 12 hours, and then the adsorption of nitrogen by the sample at different relative pressures p / p0 was measured at -196°C to obtain the adsorption-desorption isotherm. The specific surface area of ​​the sample was calculated according to the Brunauer-Emmett-Teller (BET) equation, and the total pore volume was calculated based on the nitrogen adsorption at p / p0=0.98.

[0079] Testing method for silicon-aluminum ratio: The mass contents of aluminum oxide and silicon dioxide in the molecular sieve are determined by using the 3013 X-ray fluorescence spectrometer (XRF) of Rigaku Corporation of Japan, and the silicon-aluminum ratio of the molecular sieve is obtained by calculation.

[0080] The pore diameters of the molecular sieves used in the examples and comparative examples are all above 0.6 nm.

[0081] Example 1

[0082] The Pt-containing EU-1 molecular sieve A was prepared by the following steps:

[0083] (1) Preparation of directing agent D1

[0084] 11.6 g of amorphous silicon dioxide (white carbon black) was added to 278.4 g of water, and after stirring, 0.26 g of SB powder (produced by Sasol, Germany, with an Al2O3 content of 76 wt%), 1.55 g of NaOH, and 36.07 g of trimethyl dibromide hexammonium (with a purity of 97 wt%) were added, and the mixture was stirred and mixed evenly; the reaction mixture was subjected to a first hydrothermal crystallization reaction at 110° C. under closed conditions for 18 h to prepare a directing agent D1;

[0085] The molar ratio of template, NaOH calculated as Na2O, SB powder calculated as Al2O3, water and amorphous silica calculated as SiO2 is 0.5:0.1:0.01:80:1;

[0086] (2) 5.08 g of H-β molecular sieve with a silicon-aluminum ratio of 21.8 and 0.12 g of tetraammine platinum chloride monohydrate were added to 20 g of deionized water (liquid-to-solid ratio of 3.9:1), stirred in a 90° C. water bath for 1 h, filtered, and the solid was dried at 120° C. for 2 h, and calcined at 500° C. for 4 h to obtain a first material;

[0087] The weight ratio of tetraammineplatinum chloride monohydrate to H-β molecular sieve in terms of Pt element is 1:76;

[0088] (3) Preparation of Pt-containing EU-1 molecular sieve

[0089] 5.08 g of the first material was added to 97.28 g of deionized water, and after stirring, 2.88 g of NaOH and 20.36 g of silica sol (SiO2 mass content 30%) were added and mixed evenly;

[0090] In the mixed material obtained by the above mixing, the molar ratio of the alkali metal element calculated as Na2O, the aluminum element calculated as Al2O3, water and the silicon element calculated as SiO2 is 0.2:0.02:30:1;

[0091] 51.92 g of directing agent D1 (the weight ratio of the directing agent to the weight of silicon element in the mixed material (3) calculated as SiO2 is 4.8:1) was added to the above mixture, stirred evenly, and then the second hydrothermal crystallization reaction was carried out at 180°C under closed conditions for 72 hours. After cooling to 25°C, filtering and washing the solid with deionized water, it was dried at 120°C for 6 hours and calcined at 550°C for 10 hours to obtain Pt-containing EU-1 molecular sieve A, the parameters of which are listed in Table 1;

[0092] The molecular sieve A was tested by XRD, and the results are shown in Figure 1 According to the diffraction position and relative intensity of the peak, it is known that it is EU-1 molecular sieve;

[0093] The molecular sieve A was tested by spherical aberration electron microscope, and the results are shown in Figure 2 ,according to Figure 2 It can be seen that the Pt active component is encapsulated inside the crystals of the molecular sieve.

[0094] Example 2

[0095] The Pt-containing EU-1 molecular sieve B was prepared by the following steps:

[0096] (1) Preparation of directing agent D2

[0097] 38.67 g of silica sol (SiO2 content is 30% by weight) is added to 41.19 g of water, and after stirring, 1.31 g of sodium aluminate (Al2O3 content is 45% by weight, Na2O content is 33% by weight), 0.22 g of NaOH, and 21.65 g of trimethyl dibromide hexammonium (purity is 97% by weight) are added, and the mixture is stirred and mixed evenly; the reaction mixture is subjected to a first hydrothermal crystallization reaction at 120° C. under closed conditions for 18 hours to prepare a directing agent D2;

[0098] The molar ratio of template, NaOH calculated as Na2O, sodium aluminate calculated as Al2O3, water and silica sol calculated as SiO2 is 0.3:0.05:0.03:20:1;

[0099] (2) adding 2.96 g of HY molecular sieve with a silicon-aluminum ratio of 12 and 0.24 g of tetraammine platinum chloride monohydrate to 10 g of deionized water (liquid-to-solid ratio 3.4:1), stirring and reacting in a 90° C. water bath for 1 h, filtering and drying the solid at 120° C. for 2 h, and calcining at 500° C. for 4 h to obtain a first material;

[0100] The weight ratio of tetraammineplatinum chloride monohydrate to HY molecular sieve in terms of Pt element is 1:22;

[0101] (3) Preparation of Pt-containing EU-1 molecular sieve

[0102] 2.96 g of the first material was added to 92.37 g of deionized water, and after stirring, 2.88 g of NaOH and 27.38 g of silica sol (SiO2 content of 30 wt%) were added and mixed evenly;

[0103] In the mixed material obtained by the above mixing, the molar ratio of the alkali metal element calculated as Na2O, the aluminum element calculated as Al2O3, water and the silicon element calculated as SiO2 is 0.2:0.02:30:1;

[0104] 12.98 g of directing agent D2 (the weight ratio of the directing agent to the weight of silicon element in the mixed material (3) calculated as SiO2 is 1.2:1) was added to the above mixture, stirred evenly, and then the second hydrothermal crystallization reaction was carried out at 170°C under closed conditions for 78 hours. After cooling to 25°C, filtering and washing the solid with deionized water, it was dried at 120°C for 4 hours and calcined at 550°C for 10 hours to obtain Pt-containing EU-1 molecular sieve B, the parameters of which are listed in Table 1;

[0105] XRD test on molecular sieve B shows that it is EU-1 molecular sieve;

[0106] The molecular sieve B was tested by spherical aberration electron microscope, and the results are shown in Figure 3 ,according to Figure 3 It can be seen that the Pt active component is encapsulated inside the crystals of the molecular sieve.

[0107] Example 3

[0108] The Pt-containing EU-1 molecular sieve C was prepared by the following steps:

[0109] (1) Preparation of directing agent D3

[0110] 11.6 g of amorphous silicon dioxide (white carbon black) was added to 162.38 g of water, and after stirring, 1.46 g of sodium aluminate (the content of Al2O3 was 45% by weight, the content of Na2O was 33% by weight), 0.62 g of NaOH, and 23.30 g of trimethyl dibromide hexammonium (purity was 97% by weight) were added, and the mixture was stirred and mixed evenly; the reaction mixture was subjected to a first hydrothermal crystallization reaction at 130° C. under closed conditions for 15 hours to prepare a directing agent D3;

[0111] The molar ratio of template, NaOH calculated as Na2O, sodium aluminate calculated as Al2O3, water and amorphous silicon dioxide calculated as SiO2 is 0.333:0.08:0.033:46.67:1;

[0112] (2) 5.08 g of H-β molecular sieve with a silicon-aluminum ratio of 21.8 and 0.18 g of tetraammine platinum chloride monohydrate were added to 10 g of deionized water (liquid-to-solid ratio 2:1), stirred in a 90° C. water bath for 1 h, filtered, and the solid was dried at 120° C. for 4 h, and calcined at 500° C. for 4 h to obtain a first material;

[0113] The weight ratio of tetraammineplatinum chloride monohydrate to H-β molecular sieve in terms of Pt element is 1:51;

[0114] (3) Preparation of Pt-containing EU-1 molecular sieve

[0115] 5.08 g of the first material was added to 151.21 g of deionized water, and after stirring, 2.5 g of NaOH and 5.91 g of silica sol (containing 30 wt % SiO2) were added and mixed evenly;

[0116] In the mixed material obtained by the above mixing, the molar ratio of the alkali metal element calculated as Na2O, the aluminum element calculated as Al2O3, water and the silicon element calculated as SiO2 is 0.29:0.033:80:1;

[0117] 12.95 g of directing agent D3 (the weight ratio of the directing agent to the weight of silicon element in the mixture (3) calculated as SiO2 is 2:1) was added to the above mixture, stirred evenly, and then subjected to a second hydrothermal crystallization reaction at 190°C in a sealed condition for 52 hours. Cooled to 25°C, filtered, and the solid was fully washed with deionized water, dried at 120°C for 4 hours, and calcined at 550°C for 10 hours to obtain Pt-containing EU-1 molecular sieve C, the parameters of which are listed in Table 1;

[0118] XRD test on molecular sieve C shows that it is EU-1 molecular sieve;

[0119] The molecular sieve C was tested by spherical aberration electron microscope, and the results are shown in Figure 4 ,according to Figure 4It can be seen that the Pt active component is encapsulated inside the crystals of the molecular sieve.

[0120] Example 4

[0121] The Pt-containing EU-1 molecular sieve D was prepared by the following steps:

[0122] (1) Preparation of directing agent D4

[0123] 18.03 g of silica sol (SiO2 content is 30 wt%) is added to 56.4 g of water, and after stirring, 0.88 g of sodium aluminate aqueous solution (Al2O3 content is 17.46 wt%, Na2O content is 19.11 wt%), 0.5 g of NaOH, and 10.8 g of trimethyl dibromide hexammonium (purity is 97 wt%) are added, and the mixture is stirred and mixed evenly; the reaction mixture is subjected to a first hydrothermal crystallization reaction at 120° C. under closed conditions for 18 h to prepare a directing agent D4;

[0124] The molar ratio of the template, NaOH calculated as Na2O, sodium aluminate calculated as Al2O3, water and silica sol calculated as SiO2 is 0.32:0.1:0.0167:43:1.

[0125] (2) 5.08 g of H-β molecular sieve with a silicon-aluminum ratio of 21.8 and 0.18 g of tetraammine platinum chloride monohydrate were added to 10 g of deionized water (liquid-to-solid ratio 2:1), stirred in a 90° C. water bath for 1 h, filtered, and the solid was dried at 120° C. for 4 h, and calcined at 500° C. for 4 h to obtain a first material;

[0126] The weight ratio of tetraammineplatinum chloride monohydrate to H-β molecular sieve in terms of Pt element is 1:51;

[0127] (3) Preparation of Pt-containing EU-1 molecular sieve

[0128] 5.08 g of the first material was added to 388.37 g of deionized water, and after stirring, 11.51 g of NaOH and 38.45 g of amorphous silicon dioxide (white carbon black) were added and mixed evenly;

[0129] In the mixed material obtained by the above mixing, the molar ratio of the alkali metal element calculated as Na2O, the aluminum element calculated as Al2O3, water and the silicon element calculated as SiO2 is 0.2:0.005:30:1;

[0130] 64.73 g of directing agent D4 (the weight ratio of the directing agent to the weight of silicon element in the mixture (3) calculated as SiO2 is 1.5:1) was added to the above mixture, stirred evenly, and then the second hydrothermal crystallization reaction was carried out at 190°C in a closed condition for 52 hours. After cooling to 25°C, filtering and washing the solid with deionized water, it was dried at 120°C for 4 hours and calcined at 550°C for 10 hours to obtain Pt-containing EU-1 molecular sieve D, the parameters of which are listed in Table 1;

[0131] XRD test on molecular sieve D shows that it is EU-1 molecular sieve;

[0132] The molecular sieve D was tested by spherical aberration electron microscope, and the results are shown in Figure 5 ,according to Figure 5 It can be seen that the Pt active component is encapsulated inside the crystals of the molecular sieve.

[0133] Comparative Example 1

[0134] The method of Example 1 was used to prepare Pt-containing EU-1 molecular sieve E, except that step (2):

[0135] 10.8 g of amorphous silicon dioxide (white carbon black) and 0.12 g of tetraammineplatinum chloride monohydrate were added to 20 g of deionized water, stirred in a 90° C. water bath for 1 h, filtered, and the solid was dried at 120° C. for 2 h, and calcined at 500° C. for 4 h to obtain the first material.

[0136] The molecular sieve E was tested by spherical aberration electron microscope, and the results are shown in Figure 6 ,according to Figure 6 It can be seen that the Pt active group is distributed outside the crystals of the molecular sieve, and the particles are relatively large.

[0137] Table 1

[0138] Molecular sieve number A B C D E Particle size / nm 3 or less 3 or less 3 or less 3 or less 10-20 Pt element content / weight% 0.54 1.15 1.38 0.24 0.53 Relative crystallinity / % 100 104 102 98 98 <![CDATA[Pore volume / cm 3 / g]]> 0.32 0.35 0.36 0.29 0.39 <![CDATA[Specific surface area / m 2 / g]]> 410 415 416 408 420 Silicon to aluminum ratio 42 39 28 28 43

[0139] According to the above data, the method disclosed in the present invention can be used to prepare EU-1 molecular sieves in which the Pt active component is encapsulated inside the molecular sieve crystals, and the Pt active component does not agglomerate, and the molecular sieve has a high degree of crystallinity.

[0140] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings; however, the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, a variety of simple modifications can be made to the technical solution of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0141] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0142] In addition, various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A Pt-containing EU-1 molecular sieve, characterized in that: The EU-1 molecular sieve contains a Pt active component, and at least a portion of the Pt active component is encapsulated inside the crystal of the EU-1 molecular sieve.

2. The Pt-containing EU-1 molecular sieve according to claim 1, wherein Based on the total weight of the Pt-containing EU-1 molecular sieve, the content of the Pt element is 0.03-2 wt %; The particle size of the Pt active component is less than 3 nm.

3. The Pt-containing EU-1 molecular sieve according to claim 1, wherein The relative crystallinity of the Pt-containing EU-1 molecular sieve is above 90%, and the pore volume is 0.2-0.4 cm 3 / g, specific surface area is 390-430m 2 / g, silicon-aluminum ratio is 20-300.

4. A method for preparing a Pt-containing EU-1 molecular sieve, characterized in that: The method comprises the following steps: S1, contacting a first silicon source, a first aluminum source, a first alkali source, a template agent and water to perform a first hydrothermal crystallization reaction to obtain a directing agent; S2, contacting a platinum source, a molecular sieve raw material and water for reaction, and subjecting the obtained solid product to a first heat treatment to obtain a first material; S3. Contacting the first material, an optional second silicon source, an optional second aluminum source, a second alkali source, the directing agent and water, subjecting the obtained mixture to a second hydrothermal crystallization reaction, and then subjecting the solid product obtained by the second hydrothermal crystallization reaction to a second heat treatment.

5. The method according to claim 4, wherein: The first silicon source and the second silicon source are the same or different, and independently include one or more of amorphous aluminum silicate, aluminum silicate balls, amorphous silicon dioxide, silica sol, ethyl orthosilicate, propyl orthosilicate and butyl orthosilicate; The first aluminum source and the second aluminum source are the same or different, and independently include one or more of amorphous aluminum silicate, silica-aluminum balls, sodium aluminate, aluminum sulfate, aluminum nitrate, alkoxy aluminum, aluminum oxide, aluminum sol, pseudo-boehmite and boehmite; The first alkali source and the second alkali source are the same or different, and independently include one or more of NaOH, LiOH and KOH; The platinum source includes tetraammineplatinum chloride; The template agent includes one or more of dibenzyl dimethyl ammonium salt, alkylated polymethylene α-ω diammonium salt, a precursor of dibenzyl dimethyl ammonium salt and a precursor of alkylated polymethylene α-ω diammonium salt; The molecular sieve raw material includes a molecular sieve with a pore size of 0.6 nm or more, preferably including one or more of X molecular sieve, Y molecular sieve, β molecular sieve and mercerized molecular sieve.

6. The method according to claim 4, wherein: In step S1, the molar ratio of the template, the first alkali source calculated as metal oxide, the first aluminum source calculated as Al2O3, water and the first silicon source calculated as SiO2 is (0.1-0.7): (0.05-0.3): (0.003-0.05): (10-100): 1; In step S2, the weight ratio of the platinum source calculated as Pt element to the molecular sieve raw material is 1:(20-100), and the weight ratio of the total weight of the platinum source and the molecular sieve raw material to the water is 1:(1-20); In step S3, in the mixture, the molar ratio of the alkali metal element calculated as metal oxide, the aluminum element calculated as Al2O3, water and the silicon element calculated as SiO2 is (0.1-0.3): (0.005-0.05): (10-100): 1; The weight ratio of the directing agent to the silicon element in the mixture calculated as SiO2 is (0.5-5):

1.

7. The method according to claim 4, wherein: In step S1, the conditions of the first hydrothermal crystallization reaction include: time of 10-30 hours and temperature of 90-130°C.

8. The method according to claim 4, wherein: In step S2, the contact reaction conditions include: time of 0.4-2h, temperature of 80-100°C; The conditions of the first heat treatment include: time of 2-6 hours and temperature of 450-550°C.

9. The method according to claim 4, wherein: In step S3, the conditions of the second hydrothermal crystallization reaction include: time of 40-100 hours, temperature of 160-200° C.; preferably, time of 50-80 hours, temperature of 170-190° C.; The conditions of the second heat treatment include: time of 2-12 hours and temperature of 500-600°C.

10. Pt-containing EU-1 molecular sieve prepared by the method according to any one of claims 4 to 9.

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