Bifunctional catalyst as well as preparation method and application thereof

Abstract

The invention relates to a bifunctional catalyst as well as a preparation method and application thereof. The bifunctional catalyst comprises a Pt-containing EU-1 molecular sieve and a binder component, the EU-1 molecular sieve contains a Pt active component, and at least part of the Pt active component is encapsulated in a crystal of the EU-1 molecular sieve; relative to the total weight of the bifunctional catalyst, the content of the Pt-containing EU-1 molecular sieve is 5-90 wt%, and the content of the binder component is 10-95 wt%. The catalyst is used for C8 aromatic hydrocarbon isomerization reaction, has good C8 aromatic hydrocarbon isomerization catalytic activity and stability, and has high C8 aromatic hydrocarbon yield.

Description

Technical Field

[0001] The present disclosure relates to the field of catalyst preparation, and in particular, to a bifunctional catalyst and a preparation method and application 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 its synthesis method. The synthesized EU-1 type molecular sieve SiO is prepared by uniformly mixing a silicon source, an aluminum source, an alkali metal compound, a template and water with an alkylated derivative of polymethylene α-ω-diamine ion or its precursor as a template, and then subjecting the mixture to hydrothermal crystallization. The template precursor is a parent diamine and an alcohol or an alkyl halide. 2 / Al 2 O 3 The molar ratio is 10-500.

[0005] CN1327946A discloses a method for preparing EUO structure type zeolite, the obtained zeolite and its application. The method uses dibenzyl dimethyl ammonium salt and nitrogen-containing organic structure agent Q corresponding to the precursor of the salt, and uses EUO zeolite seed crystals to synthesize SiO 2 / Al 2 O 3 The EUO type molecular sieve with a molar ratio of 10-100 can be used for aromatic isomerization reaction and can reduce the net loss caused by side reactions.

[0006] CN99126910.1 reports EUO zeolite containing crystals and crystal aggregates with a specific particle distribution and its use as an isomerization C 8 Application of catalysts for aromatic hydrocarbons. This patent uses alkylated polymethylene α-ω-diamine ions as templates, and controls the reaction temperature and different stirring rates to make the particle distribution Dv,90 value of zeolite aggregates less than or equal to 500μm, which is used for C 8 Aromatic isomerization with relatively high ethylbenzene conversion. Summary of the invention

[0007] The purpose of the present invention is to provide a bifunctional catalyst and a preparation method and application thereof. 8 Aromatic isomerization reaction, with good C 8Aromatic isomerization catalytic activity and stability, and has a high C 8 Aromatics yield.

[0008] In order to achieve the above-mentioned object, the first aspect of the present disclosure provides a bifunctional catalyst, wherein the bifunctional catalyst comprises a Pt-containing EU-1 molecular sieve and a binder component;

[0009] 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;

[0010] Relative to the total weight of the bifunctional catalyst, the content of the Pt-containing EU-1 molecular sieve is 5-90 wt %, and the content of the binder component is 10-95 wt %.

[0011] Optionally, the binder component includes one or more of aluminum oxide, silicon dioxide and phosphorus pentoxide.

[0012] The second aspect of the present disclosure provides a method for preparing a bifunctional catalyst, the method comprising: mixing a Pt-containing EU-1 molecular sieve with a binder, and then performing a molding process;

[0013] 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.

[0014] 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.

[0015] Optionally, 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;

[0016] The particle size of the Pt active component is less than 3 nm.

[0017] Optionally, the method for preparing the Pt-containing EU-1 molecular sieve comprises the following steps:

[0018] 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;

[0019] 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;

[0020] 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.

[0021] 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;

[0022] 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;

[0023] 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;

[0024] The platinum source includes tetraammineplatinum chloride;

[0025] 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;

[0026] 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.

[0027] Optionally, in step S1, the template, the first alkali source in terms of metal oxide, and the first alkali source in terms of Al 2 O 3 The first aluminum source, water and SiO 2 The molar ratio of the first silicon source is (0.1-0.7): (0.05-0.3): (0.003-0.05): (10-100): 1;

[0028] 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);

[0029] In step S3, in the mixture, the alkali metal elements in terms of metal oxides and the Al 2 O 3 Aluminum, water and SiO 2The molar ratio of silicon element is (0.1-0.3):(0.005-0.05):(10-100):1;

[0030] The weight of the directing agent is equal to the weight of SiO 2 The weight ratio of silicon element is (0.5-5):1.

[0031] Optionally, in step S1, the conditions of the first hydrothermal crystallization reaction include: time of 10-30h, temperature of 90-130°C.

[0032] Optionally, in step S2, the contact reaction conditions include: time of 0.4-2h, temperature of 80-100°C;

[0033] The conditions of the first heat treatment include: time of 2-6 hours and temperature of 450-550°C.

[0034] 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.;

[0035] The conditions of the second heat treatment include: time of 2-12 hours and temperature of 500-600°C.

[0036] Optionally, the binder includes one or more of SB powder, silicon dioxide and phosphorus pentoxide;

[0037] The weight ratio of the Pt-containing EU-1 molecular sieve to the binder calculated as oxide is (5-90):(10-95).

[0038] Optionally, the method comprises the following steps:

[0039] a. mixing the Pt-containing EU-1 molecular sieve, the extrusion aid, the peptizing agent and the binder, and performing the molding process to obtain a first product;

[0040] b. subjecting the first product to a first drying treatment and a third heat treatment to obtain a second product;

[0041] c. contacting the second product with an ion exchange liquid to perform ion exchange treatment to obtain a third product;

[0042] d. subjecting the third product to a second drying treatment and a fourth heat treatment;

[0043] Alternatively, the method comprises the following steps:

[0044] A. contacting the Pt-containing EU-1 molecular sieve with an ion exchange liquid to perform an ion exchange treatment to obtain a fourth product;

[0045] B. subjecting the fourth product to a third drying treatment and a fifth heat treatment to obtain a fifth product;

[0046] C. mixing the fifth product, the extrusion aid, the peptizing agent and the binder, and performing the molding process to obtain the sixth product;

[0047] D. subjecting the sixth product to a fourth drying treatment and a sixth heat treatment;

[0048] Optionally, the ion exchange solution includes an acid solution or an ammonium salt solution;

[0049] The acid solution includes one or more of hydrochloric acid solution, nitric acid solution and sulfuric acid solution;

[0050] The ammonium salt in the ammonium salt solution includes one or more of ammonium chloride, ammonium nitrate, ammonium sulfate, ammonium carbonate and ammonium bicarbonate;

[0051] The conditions of the ion exchange treatment include: time of 0.5-6h, temperature of 60-100°C;

[0052] Optionally, the conditions of the first drying treatment, the second drying treatment, the third drying treatment and the fourth drying treatment are the same or different, and respectively include: a time of 80-120° C., a time of 1-10 h;

[0053] Optionally, the conditions of the third heat treatment, the fourth heat treatment, the fifth heat treatment and the sixth heat treatment are the same or different, and respectively include: time of 2-10h, temperature of 500-600°C.

[0054] Optionally, step a comprises: treating the Pt-containing EU-1 molecular sieve at 400-540° C. for 2-6 hours under a hydrogen atmosphere, and then performing the molding treatment;

[0055] Optionally, step A comprises: treating the Pt-containing EU-1 molecular sieve at 400-540° C. for 2-6 hours under a hydrogen atmosphere, and then performing the ion exchange treatment.

[0056] A third aspect of the present disclosure provides a bifunctional catalyst prepared by the method described in the second aspect of the present disclosure.

[0057] The fourth aspect of the present disclosure provides a C 8 A method for isomerization of aromatic hydrocarbons, the method comprising: in the presence of a catalyst, 8Aromatic hydrocarbons are contacted with hydrogen and reacted, and the catalyst includes the bifunctional catalyst described in the first aspect or the third aspect of the present disclosure.

[0058] Optionally, the method further comprises: before carrying out the reaction, contacting the bifunctional catalyst with a hydrogen atmosphere for reduction treatment;

[0059] The reduction treatment conditions include: time of 0.5-10h and temperature of 250-600°C.

[0060] Optionally, the reaction conditions include: a temperature of 300-500°C, a pressure of 0.3-1.5 MPa, the hydrogen and the C 8 The molar ratio of aromatic hydrocarbons is (1-10): 1, with the C 8 The feed mass space velocity of aromatics is 1-10h -1 .

[0061] Through the above technical scheme, the catalyst disclosed in the present invention uses Pt-containing EU-1 molecular sieve as an acidic component and a noble metal hydrogenation and dehydrogenation component to prepare a bifunctional catalyst. The Pt active component in the Pt-containing EU-1 molecular sieve does not agglomerate, and the molecular sieve has a high crystallinity. The prepared bifunctional catalyst is used for C 8 Aromatic isomerization reaction, with good C 8 Aromatic isomerization catalytic activity and stability, and has a high C 8 Aromatics yield.

[0062] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] 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:

[0064] 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.

[0065] 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.

[0066] Figure 3 This is a transmission electron microscope image of catalyst D-1 prepared in comparative example 1 of the present disclosure. DETAILED DESCRIPTION

[0067] 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.

[0068] The first aspect of the present disclosure provides a bifunctional catalyst, the bifunctional catalyst comprising a Pt-containing EU-1 molecular sieve and a binder component;

[0069] 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;

[0070] Relative to the total weight of the bifunctional catalyst, the content of the Pt-containing EU-1 molecular sieve is 5-90 wt %, and the content of the binder component is 10-95 wt %.

[0071] In the present disclosure, "at least part of the Pt active components are encapsulated inside the crystals of the molecular sieve" means that part or all of the Pt active components exist inside the crystals of the EU-1 molecular sieve, preferably all of the Pt active components exist inside the crystals of the EU-1 molecular sieve.

[0072] According to one embodiment of the present disclosure, relative to the total weight of the bifunctional catalyst, the content of the Pt-containing EU-1 molecular sieve is 10-80 wt %, and the content of the binder component is 20-90 wt %.

[0073] According to one embodiment of the present disclosure, the binder component includes one or more of aluminum oxide, silicon dioxide, and phosphorus pentoxide.

[0074] A second aspect of the present disclosure provides a method for preparing a bifunctional catalyst, the method comprising the following steps:

[0075] The Pt-containing EU-1 molecular sieve is mixed with a binder and then subjected to a molding process;

[0076] 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.

[0077] According to one embodiment of the present disclosure, based on the total weight of the Pt-containing EU-1 molecular sieve, the content of Pt element is 0.03-2% by weight, preferably 0.05-1.5% by weight; the above content can reduce the cost while maintaining the catalyst activity.

[0078] According to one embodiment of the present disclosure, the particle size of the Pt active component is less than 3 nm, preferably less than 2 nm, and more preferably 0.5-1.5 nm.

[0079] According to one embodiment of the present disclosure, the relative crystallinity of the molecular sieve is above 90%, preferably above 95%, and the calculation basis of the relative crystallinity is the EU-1 molecular sieve synthesized by hydrothermal crystallization method using trimethyl hexammonium dibromide as template in Chinese patent application CN99126910.1.

[0080] According to one embodiment of the present disclosure, the pore volume of the molecular sieve is 0.2-0.4 cm 3 / g, specific surface area is 390-430m 2 / g, the silicon-aluminum ratio is 20-300, preferably 25-100; wherein the silicon-aluminum ratio refers to the SiO 2 and Al 2 O 3 molar ratio.

[0081] According to one embodiment of the present disclosure, the method for preparing Pt-containing EU-1 molecular sieve comprises the following steps:

[0082] 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;

[0083] 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;

[0084] 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.

[0085] In the present disclosure, the first material is a Pt ion exchanged molecular sieve, which is subjected to a hydrothermal crystallization reaction by a crystal transformation method 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 crystallinity; the bifunctional catalyst prepared by using the EU-1 molecular sieve as an acidic component and a noble metal hydrodehydrogenation component is used for C 8 Aromatic isomerization reaction, with good C 8 Aromatic isomerization catalytic activity and stability, as well as high selectivity for target products, and has high C 8 Aromatics yield.

[0086] In the present disclosure, the heat treatment method is conventional in the art, for example, it may be calcination.

[0087] 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.

[0088] 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.

[0089] According to one embodiment of the present disclosure, the template includes one or more of dibenzyl dimethyl ammonium salt, alkylated polymethylene α-ω diammonium salt, precursor of dibenzyl dimethyl ammonium salt and precursor of alkylated polymethylene α-ω diammonium salt. 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.

[0090] 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.

[0091] According to one embodiment of the present disclosure, in step S1, the template, the first alkali source in terms of metal oxide, and the Al 2 O 3 The first aluminum source, water and SiO 2 The molar ratio of the first silicon source 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 NaOH. 2 O plan.

[0092] 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).

[0093] According to an embodiment of the present disclosure, in step S3, in a mixture comprising the first material, the second silicon source, the second aluminum source, the second alkali source and the water, an alkali metal oxide, an Al 2 O 3 Aluminum, water and SiO 2 The molar ratio of silicon element is (0.1-0.3):(0.005-0.05):(10-100):1.

[0094] According to one embodiment of the present disclosure, in step S3, the directing agent and the SiO 2 The weight ratio of silicon element is (0.5-5):1.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] 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.

[0099] 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.

[0100] 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.

[0101] 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.

[0102] 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.

[0103] According to one embodiment of the present disclosure, the method comprises the following steps:

[0104] a. mixing the Pt-containing EU-1 molecular sieve, the extrusion aid, the peptizing agent and the binder, and performing the molding process to obtain a first product;

[0105] b. subjecting the first product to a first drying treatment and a third heat treatment to obtain a second product;

[0106] c. contacting the second product with an ion exchange liquid to perform ion exchange treatment to obtain a third product;

[0107] d. subjecting the third product to a second drying treatment and a fourth heat treatment.

[0108] According to one embodiment of the present disclosure, the method comprises the following steps:

[0109] A. contacting the Pt-containing EU-1 molecular sieve with an ion exchange liquid to perform an ion exchange treatment to obtain a fourth product;

[0110] B. subjecting the fourth product to a third drying treatment and a fifth heat treatment to obtain a fifth product;

[0111] C. mixing the fifth product, the extrusion aid, the peptizing agent and the binder, and performing the molding process to obtain the sixth product;

[0112] D. subjecting the sixth product to a fourth drying treatment and a sixth heat treatment.

[0113] According to one embodiment of the present disclosure, the mass ratio of the Pt-containing EU-1 molecular sieve to the binder calculated as oxide is (5-90):(10-95), preferably (10-80):(20-90).

[0114] According to one embodiment of the present disclosure, the binder includes one or more of SB powder, silicon dioxide and phosphorus pentoxide.

[0115] According to one embodiment of the present disclosure, the ion exchange treatment is carried out under continuous stirring conditions; the conditions include: time is 0.5-6h, temperature is 60-100°C, and the liquid-solid weight ratio of the ion exchange liquid to the molecular sieve or the second product is (1-10):1; the ion exchange treatment can be repeated multiple times, for example, it can be carried out twice.

[0116] According to one embodiment of the present disclosure, the ion exchange liquid includes an acid solution or an ammonium salt solution. When the ion exchange liquid is an acid solution, the concentration of the acid solution is 1-10 weight %; when the ion exchange liquid is an ammonium salt solution, the concentration of the ammonium salt solution is 1-10 weight %; the acid solution includes one or more of a hydrochloric acid solution, a nitric acid solution and a sulfuric acid solution; the ammonium salt in the ammonium salt solution includes one or more of ammonium chloride, ammonium nitrate, ammonium sulfate, ammonium carbonate and ammonium bicarbonate.

[0117] According to one embodiment of the present disclosure, step a comprises: treating the Pt-containing EU-1 molecular sieve at 400-540° C. for 2-6 hours under a hydrogen atmosphere, and then performing a molding treatment.

[0118] According to one embodiment of the present disclosure, step A comprises: treating the Pt-containing EU-1 molecular sieve at 400-540° C. for 2-6 hours under a hydrogen atmosphere, and then performing the ion exchange treatment.

[0119] According to one embodiment of the present disclosure, the conditions of the first drying treatment, the second drying treatment, the third drying treatment and the fourth drying treatment are the same or different, and respectively include: time is 80-120°C, time is 1-10h; preferably, temperature is 100-120°C, time is 2-6h; the drying treatment method is conventional in the art and will not be elaborated here.

[0120] According to one embodiment of the present disclosure, the conditions of the third heat treatment, the fourth heat treatment, the fifth heat treatment and the sixth heat treatment are the same or different, and respectively include: time is 2-10h, temperature is 500-600°C; preferably, time is 3-5h, temperature is 500-550°C.

[0121] In the present disclosure, the molding method is conventional in the art, for example, it can be extrusion molding, tablet molding, drop ball molding, spray molding or rolling molding, preferably extrusion molding; specifically, step a includes: mixing molecular sieve, binder, extrusion aid and peptizing agent, and then performing molding treatment, relative to the total weight of molecular sieve and binder, the amount of extrusion aid is 0.5-5 weight%; step C includes: mixing the fifth product, extrusion aid, peptizing agent and binder, and performing molding treatment, relative to the total weight of the fifth product and binder, the amount of extrusion aid is 0.5-5 weight%; the extrusion aid can include one or more of field sesbania powder, starch and methyl cellulose; the peptizing agent includes one or more of dilute nitric acid, oxalic acid, citric acid and tartaric acid; the concentration of nitric acid is preferably 1-8% by volume, and the concentration of the remaining acids is preferably 1-5% by volume; the amount of peptizing agent is conventional in the art.

[0122] A third aspect of the present disclosure provides a bifunctional catalyst prepared by the method described in the second aspect of the present disclosure.

[0123] The above-mentioned bifunctional catalyst has the same characteristics as the bifunctional catalyst described in the first aspect of the present disclosure, which will not be described in detail here.

[0124] The fourth aspect of the present disclosure provides a C 8 A method for isomerization of aromatic hydrocarbons, the method comprising: in the presence of a catalyst, 8 Aromatic hydrocarbons are contacted with hydrogen and reacted, and the catalyst includes the bifunctional catalyst described in the first aspect or the third aspect of the present disclosure.

[0125] According to one embodiment of the present disclosure, the method further comprises: before carrying out the reaction, contacting the bifunctional catalyst with hydrogen for reduction treatment; the conditions of the reduction treatment include: time of 0.5-10h, temperature of 250-600°C, preferably 300-500°C.

[0126] According to one embodiment of the present disclosure, the reaction conditions include: a temperature of 300-500°C, preferably 350-420°C; a pressure of 0.3-1.5MPa, preferably 0.4-1.0MPa; the hydrogen and the C 8 The molar ratio of aromatic hydrocarbons (hydrogen / hydrocarbon ratio) is (1-10):1, preferably (2-8):1; 8 The feed mass space velocity of aromatics is 1-10h -1 , preferably 2-6h -1 .

[0127] 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.

[0128] 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°.

[0129] 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.

[0130] Test method and instrument model of transmission electron microscope: The morphology of the samples was tested on a FEI Tecnai F20 transmission electron microscope with an accelerating voltage of 200 kV.

[0131] 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.

[0132] 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%.

[0133] Particle size testing method: STEM.

[0134] 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, and the instrument used was Micromeritics ASAP 2420. The test conditions were that the sample was vacuum degassed at 350°C for 12 hours, and then different relative pressures p / p were measured at -196°C. 0 The adsorption of nitrogen by the sample was measured 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 according to p / p 0 = 0.98 nitrogen adsorption amount was calculated.

[0135] 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.

[0136] The pore diameters of the molecular sieves used in the examples and comparative examples are all above 0.6 nm.

[0137] The contents of molecular sieve and binder components in the catalyst are calculated based on the raw material composition.

[0138] Example 1

[0139] The bifunctional catalyst A-1 was prepared by the following steps:

[0140] (1) Preparation of directing agent D1

[0141] 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, Al 2 O 3 The content is 76 wt %), 1.55 g of NaOH, and 36.07 g of trimethyl dibromide hexammonium (purity is 97 wt %), and the mixture is stirred and mixed evenly; the reaction mixture is subjected to a first hydrothermal crystallization reaction at 110° C. in a sealed condition for 18 h to prepare a directing agent D1;

[0142] Template agent, Na 2 O-based NaOH, Al 2 O 3 SB powder, water and SiO 2 The molar ratio of amorphous silicon dioxide is 0.5:0.1:0.01:80:1;

[0143] (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;

[0144] The weight ratio of tetraammineplatinum chloride monohydrate to H-β molecular sieve in terms of Pt element is 1:76;

[0145] (3) Preparation of Pt-containing EU-1 molecular sieve

[0146] 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 (SiO 2 Mass content 30%) mixed evenly;

[0147] In the mixed material obtained by mixing above, Na 2 Alkali metal elements, measured in terms of O, 2 O 3 Aluminum, water and SiO 2 The molar ratio of silicon element is 0.2:0.02:30:1;

[0148] 51.92 g of directing agent D1 (the weight of the directing agent and the SiO 2 The weight ratio of silicon element is 4.8:1) 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;

[0149] 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;

[0150] 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;

[0151] (4) Preparation of bifunctional catalysts

[0152] 5 g of molecular sieve A, 7 g of SB powder (produced by Sasol, Germany, Al 2 O 3 content of 76% by weight), 0.2g of sesbania powder and 10g of a 3% by volume dilute nitric acid solution were mixed evenly, kneaded and extruded into strips to obtain a first product;

[0153] The amount of sesbania powder used was 1.67 wt % relative to the total weight of molecular sieve A and SB powder;

[0154] Molecular sieve A and Al 2 O 3 The weight ratio of SB powder was 48.5:51.5;

[0155] The first product was dried at 120°C for 4 hours and calcined at 550°C for 5 hours to obtain a second product;

[0156] 8 g of the second product was treated with 60 mL of an aqueous solution of ammonium chloride at 95° C. and stirred for 2 h for ion exchange, and the same conditions were repeated once to obtain a third product.

[0157] The liquid-to-solid weight ratio of the ion exchange liquid to the second product is 7.5:1, and the concentration of ammonium chloride in the ammonium chloride aqueous solution is 1.6 weight %;

[0158] The third product was fully washed with deionized water, dried at 120°C for 6 hours, and calcined at 500°C for 4 hours to obtain a bifunctional catalyst A-1. The composition of the catalyst is listed in Table 1.

[0159] Example 2

[0160] The bifunctional catalyst B-1 was prepared by the following steps:

[0161] (1) Preparation of directing agent D2

[0162] 38.67 g silica sol (SiO 2 30 mass %) was added to 41.19 g of water, and after stirring, 1.31 g of sodium aluminate (Al 2 O 3 The content of Na 2 O content 33 wt %), 0.22 g of NaOH, 21.65 g of trimethyl dibromide hexammonium (purity 97 wt %), stirring and mixing evenly; subjecting the above reaction mixture to a first hydrothermal crystallization reaction at 120° C. in a sealed condition for 18 h to prepare a directing agent D2;

[0163] Template agent, Na 2 O-based NaOH, Al 2 O 3 Sodium aluminate, water and SiO 2 The molar ratio of the silica sol is 0.3:0.05:0.03:20:1;

[0164] (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;

[0165] The weight ratio of tetraammineplatinum chloride monohydrate to HY molecular sieve in terms of Pt element is 1:22;

[0166] (3) Preparation of Pt-containing EU-1 molecular sieve

[0167] 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 (SiO 2 The content is 30 weight %) and mixed evenly;

[0168] In the mixed material obtained by mixing above, Na 2 Alkali metal elements, measured in terms of O, 2 O 3 Aluminum, water and SiO 2 The molar ratio of silicon element is 0.2:0.02:30:1;

[0169] 12.98 g of directing agent D2 (the weight of the directing agent and the SiO2 The weight ratio of silicon element is 1.2:1) 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;

[0170] XRD test on molecular sieve B shows that it is EU-1 molecular sieve;

[0171] The spherical aberration electron microscopy test on molecular sieve B shows that the Pt active component is encapsulated inside the crystal of the molecular sieve;

[0172] (4) Preparation of bifunctional catalysts

[0173] 8 g of molecular sieve B, 15 g of SB powder (produced by Sasol, Germany, Al 2 O 3 content of 76% by weight), 1g of sesbania powder and 18g of a dilute nitric acid solution with a concentration of 6% by volume were mixed evenly, kneaded and then extruded into strips to obtain a first product;

[0174] The amount of sesbania powder used was 4.35 wt % relative to the total weight of molecular sieve B and SB powder;

[0175] Molecular sieve B with Al 2 O 3 The weight ratio of SB powder was 41.2:58.8;

[0176] The first product was dried at 120°C for 4 hours and calcined at 550°C for 5 hours to obtain a second product;

[0177] 12 g of the second product was subjected to ion exchange treatment with 120 mL of ammonium nitrate aqueous solution at 90° C. with continuous stirring for 2 h, and the same conditions were repeated once to obtain a third product;

[0178] The liquid-to-solid weight ratio of the ion exchange liquid to the second product is 10:1 in the aqueous ammonium nitrate solution, and the concentration of ammonium nitrate is 3.37% by weight;

[0179] The third product was fully washed with deionized water, dried at 110°C for 6 hours, and calcined at 500°C for 6 hours to obtain a bifunctional catalyst B-1. The composition of the catalyst is listed in Table 1.

[0180] Example 3

[0181] The bifunctional catalyst C-1 was prepared by the following steps:

[0182] (1) Preparation of directing agent D3

[0183] 11.6 g of amorphous silicon dioxide (white carbon black) was added to 162.38 g of water, and then 1.46 g of sodium aluminate (Al 2 O 3 The content of Na 2 O content is 33 wt %), 0.62 g of NaOH, 23.30 g of trimethyl dibromide hexammonium (purity is 97 wt %), and stirred to mix evenly; the reaction mixture was subjected to a first hydrothermal crystallization reaction at 130° C. in a sealed condition for 15 h to prepare a directing agent D3;

[0184] Template agent, Na 2 O-based NaOH, Al 2 O 3 Sodium aluminate, water and SiO 2 The molar ratio of amorphous silicon dioxide is 0.333:0.08:0.033:46.67:1;

[0185] (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, and calcined at 500° C. for 4 h to obtain a first material;

[0186] The weight ratio of tetraammineplatinum chloride monohydrate to H-β molecular sieve in terms of Pt element is 1:51;

[0187] (3) Preparation of Pt-containing EU-1 molecular sieve

[0188] 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 (SiO 2 The content is 30% by weight) and mixed evenly;

[0189] In the mixed material obtained by mixing above, Na 2 Alkali metal elements, measured in terms of O, 2 O 3 Aluminum, water and SiO 2 The molar ratio of silicon element is 0.29:0.033:80:1;

[0190] 12.95 g of directing agent D3 (the weight of the directing agent and the SiO 2The weight ratio of silicon element is 2:1) added to the above mixture, stirred evenly and then subjected to a second hydrothermal crystallization reaction at 190°C in a sealed condition for 52h. Cooled to 25°C, filtered and the solid was fully washed with deionized water, dried at 120°C for 4h, and calcined at 550°C for 10h to obtain Pt-containing EU-1 molecular sieve C, the parameters of which are listed in Table 1;

[0191] XRD test on molecular sieve C shows that it is EU-1 molecular sieve;

[0192] The spherical aberration electron microscopy test of molecular sieve C shows that the Pt active component is encapsulated inside the crystal of the molecular sieve;

[0193] (4) Preparation of bifunctional catalysts

[0194] 5 g molecular sieve C, 20 g SB powder (produced by Sasol, Germany, Al 2 O 3 The content is 76% by weight), 1g of sesbania powder and 20g of a 3% by volume dilute nitric acid solution are mixed evenly, kneaded and then extruded to obtain a first product;

[0195] The amount of sesbania powder was 4.0 wt % relative to the total weight of molecular sieve C and SB powder;

[0196] Molecular sieve C and Al 2 O 3 The weight ratio of SB powder was 24.8:75.2;

[0197] The first product was dried at 120°C for 4 hours and calcined at 550°C for 5 hours to obtain a second product;

[0198] 12 g of the second product was treated with 100 mL of an aqueous solution of ammonium sulfate at 85° C. and stirred for 2 h for ion exchange, and the same conditions were repeated once to obtain a third product.

[0199] The liquid-to-solid weight ratio of the ion exchange liquid to the second product is 8.3:1, and the concentration of ammonium sulfate in the ammonium sulfate aqueous solution is 1.4 weight %;

[0200] The third product was fully washed with deionized water, dried at 110°C for 6 hours, and calcined at 500°C for 4 hours to obtain a bifunctional catalyst C-1. The composition of the catalyst is listed in Table 1.

[0201] Example 4

[0202] The molecular sieve C prepared in Example 3 was reduced at 500° C. for 2 h in a hydrogen atmosphere to obtain a reduced Pt-containing EU-1 molecular sieve C. 5 g of the reduced molecular sieve C and 20 g of SB powder (produced by Sasol, Germany, Al 2 O3 The content is 76% by weight), 1g of sesbania powder and 20g of a 3% by volume dilute nitric acid solution are mixed evenly, kneaded and then extruded to obtain a first product;

[0203] The amount of sesbania powder was 4.0 wt % relative to the total weight of molecular sieve C and SB powder;

[0204] Reduced molecular sieve C and Al 2 O 3 The weight ratio of SB powder was 24.8:75.2;

[0205] The first product was dried at 120°C for 4 hours and calcined at 550°C for 5 hours to obtain a second product;

[0206] 12 g of the second product was treated with 100 mL of an aqueous solution of ammonium sulfate at 85° C. and stirred for 2 h for ion exchange, and the same conditions were repeated once to obtain a third product.

[0207] The liquid-to-solid weight ratio of the ion exchange liquid to the second product is 8.3:1, and the concentration of ammonium sulfate in the ammonium sulfate aqueous solution is 1.4 weight %;

[0208] The third product was fully washed with deionized water, dried at 110°C for 6 hours, and calcined at 500°C for 4 hours to obtain a bifunctional catalyst D-1. The composition of the catalyst is listed in Table 1.

[0209] Example 5

[0210] 10 g of the molecular sieve C prepared in Example 3 was treated with 100 mL of an aqueous solution of ammonium sulfate at 85° C. and continuously stirred for 2 h for ion exchange, and the same conditions were repeated once to obtain a fourth product;

[0211] The liquid-to-solid weight ratio of the ion exchange liquid to the molecular sieve C is 10:1, and the concentration of ammonium sulfate in the ammonium sulfate aqueous solution is 1.4 weight %;

[0212] The fourth product was fully washed with deionized water, dried at 110°C for 6 hours, and calcined at 500°C for 4 hours to obtain the fifth product;

[0213] 5 g of the fifth product and 20 g of SB powder (produced by Sasol, Germany, Al 2 O 3 The content is 76% by weight), 1g of sesbania powder and 20g of a 3% by volume dilute nitric acid solution are mixed evenly, kneaded and then extruded to obtain a sixth product;

[0214] The amount of sesbania powder used is 4.0 wt % relative to the total weight of the fifth product and SB powder;

[0215] The fifth product is Al2 O 3 The weight ratio of SB powder was 24.8:75.2;

[0216] The sixth product was dried at 120°C for 4 hours and calcined at 550°C for 5 hours to obtain a bifunctional catalyst E-1. The composition of the catalyst is listed in Table 1.

[0217] Example 6

[0218] The bifunctional catalyst F-1 was prepared by the method of Example 3, except that the molecular sieve F was prepared by the following steps:

[0219] (1) Preparation of directing agent D4

[0220] 38.67 g silica sol (SiO 2 30 wt %) was added to 41.19 g of water, and after stirring, 1.31 g of sodium aluminate (Al 2 O 3 The content of Na 2 O content is 33 wt %), 0.22 g of NaOH, 21.65 g of trimethyl dibromide hexammonium (purity is 97 wt %), and stirred to mix evenly; the reaction mixture was subjected to a first hydrothermal crystallization reaction at 120° C. in a sealed condition for 18 h to prepare a directing agent D4;

[0221] Template agent, Na 2 O-based NaOH, Al 2 O 3 Sodium aluminate, water and SiO 2 The molar ratio of the silica sol is 0.3:0.05:0.03:20:1;

[0222] (2) adding 2.96 g of HY molecular sieve with a silicon-aluminum ratio of 12 and 0.32 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;

[0223] The weight ratio of tetraammineplatinum chloride monohydrate to HY molecular sieve is 1:17, calculated on the basis of Pt element;

[0224] (3) Preparation of Pt-containing EU-1 molecular sieve

[0225] 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 (SiO 2 The content is 30 weight %) and mixed evenly;

[0226] In the mixed material obtained by mixing above, Na 2 Alkali metal elements, measured in terms of O, 2 O 3 Aluminum, water and SiO 2 The molar ratio of silicon element is 0.2:0.02:30:1;

[0227] 12.98 g of directing agent D4 (the weight of the directing agent and the SiO 2 The weight ratio of silicon element is 1.2:1) 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 F, the parameters of which are listed in Table 1;

[0228] XRD test on molecular sieve F shows that it is EU-1 molecular sieve;

[0229] The results of spherical aberration electron microscopy test on molecular sieve F show that the Pt active component is encapsulated inside the crystal of the molecular sieve; the parameters of the bifunctional catalyst F-1 are listed in Table 1.

[0230] Example 7

[0231] The molecular sieve C prepared in Example 3 was used to prepare the bifunctional catalyst G-1:

[0232] 2g molecular sieve C, 25g SB powder (produced by Sasol, Germany, Al 2 O 3 The content is 76% by weight), 1g of sesbania powder and 20g of a 3% by volume dilute nitric acid solution are mixed evenly, kneaded and then extruded to obtain a first product;

[0233] The amount of sesbania powder was 3.7 wt % relative to the total weight of molecular sieve C and SB powder;

[0234] Molecular sieve C and Al 2 O 3 The weight ratio of the SB powder was 9.5:90.5;

[0235] The first product was dried at 120°C for 4 hours and calcined at 550°C for 5 hours to obtain a second product;

[0236] 12 g of the second product was treated with 100 mL of an aqueous solution of ammonium sulfate at 85° C. and stirred for 2 h for ion exchange, and the same conditions were repeated once to obtain a third product.

[0237] The liquid-to-solid weight ratio of the ion exchange liquid to the second product is 8.3:1, and the concentration of ammonium sulfate in the ammonium sulfate aqueous solution is 1.4 weight %;

[0238] The third product was washed thoroughly with deionized water, dried at 110°C for 6 hours, and calcined at 500°C for 4 hours to obtain a bifunctional catalyst G-1. The composition of the catalyst is listed in Table 1.

[0239] Comparative Example 1

[0240] Catalyst H-1 was prepared by the following steps:

[0241] 23.30 g of trimethyl hexammonium dibromide (purity 97 wt%) was added to 130 g of water, and then 40 g of silica sol (SiO 2 Content is 29 weight %), forming a first solution;

[0242] 2.10 g of NaOH, 1.46 g of sodium aluminate (Al 2 O 3 The content is 45% by weight, Na 2 O content of 33 wt %) was dissolved in 16 g of water to form a second solution;

[0243] Under stirring, the second solution was added to the first solution, and 16.38 g of water was added, and the mixture was stirred thoroughly to obtain a mixture;

[0244] The mixture was crystallized at 180°C for 40h, cooled to 25°C, the solid was collected and washed with deionized water, dried at 110°C for 10h, and calcined at 550°C for 5h to obtain molecular sieve H. The parameters are listed in Table 1. XRD showed that it was EU-1 molecular sieve.

[0245] (2) Preparation of Catalyst

[0246] 10 g of EU-1 molecular sieve H prepared in step (1), 14 g of SB powder (produced by Sasol, Germany, Al 2 O 3 content of 76 weight %), 0.4g sesbania powder and 20g of a 3 volume % dilute nitric acid solution were mixed evenly, kneaded and extruded into strips, dried at 120°C for 4h, and calcined at 550°C for 5h to obtain a first product;

[0247] 12 g of the first product was subjected to ion exchange with 90 mL of 5 wt % ammonium chloride aqueous solution at 95° C. with continuous stirring for 2 h, and the exchange was repeated once under the same conditions to obtain a second product;

[0248] The second product was fully washed with deionized water, dried at 120°C for 6 hours, and calcined at 500°C for 4 hours to obtain a third product;

[0249] 11 g of the third product was taken, immersed in 10 mL of chloroplatinic acid solution with a platinum content of 3.36 mg / mL at 25°C for 24 h, dried at 120°C for 6 h, and calcined at 500°C for 6 h to obtain catalyst H-1, the composition of which is listed in Table 1.

[0250] Catalyst H-1 was tested by transmission electron microscopy, and the results are as follows Figure 3 As shown, according to Figure 3 It can be seen that the Pt active components in catalyst H-1 are agglomerates.

[0251] Comparative Example 2

[0252] Catalyst I-1 was prepared by the method of Example 1, except that, in step (2):

[0253] 10.8 g of amorphous silicon dioxide (white carbon black) and 0.12 g of tetraammine platinum 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 a first material;

[0254] The spherical aberration electron microscopy test of molecular sieve I shows that the Pt active component is distributed outside the crystals of the molecular sieve, and the particles are relatively large.

[0255] (4) Preparation of Catalyst

[0256] 5 g of Pt-containing EU-1 molecular sieve I, 7 g of SB powder (produced by Sasol, Germany, Al 2 O 3 content of 76% by weight), 0.2g of sesbania powder and 10g of a 3% by volume dilute nitric acid solution were mixed evenly, kneaded and then extruded to obtain a first product;

[0257] The first product was dried at 120°C for 4 hours and calcined at 550°C for 5 hours to obtain a second product;

[0258] 8 g of the second product was subjected to ion exchange with 60 mL of 5.0 wt % ammonium chloride aqueous solution at 95° C. and under continuous stirring for 2 h, and the exchange was repeated once under the same conditions to obtain the second product;

[0259] The second product was washed thoroughly with deionized water, dried at 120°C for 6 hours, and calcined at 500°C for 4 hours to obtain catalyst I-1. The composition of the catalyst is listed in Table 1.

[0260] Table 1

[0261]

[0262]

[0263] Test Case

[0264] The following example evaluates the C 8 Aromatic isomerization performance.

[0265] The catalysts prepared in the above examples and comparative examples were subjected to reduction treatment: reduction treatment was performed at 500° C. for 4 h under a hydrogen atmosphere to obtain catalysts A-2 to I-2.

[0266] Stainless steel reactor in a continuous flow fixed bed small reactor 0.5 g of catalyst was loaded into the mixture. The raw material mass composition is: C 8 Nonaromatics 1.23 wt%, ethylbenzene 3.99 wt%, m-xylene 65.56 wt%, o-xylene 29.18 wt%, p-xylene 0.03 wt%.

[0267] During the evaluation, the hydrogen flow rate was controlled by a mass flow meter, the raw material was fed into the buffer tank by a metering pump, the two were mixed and then entered the reactor to contact with the hot catalyst for reaction, the reaction product entered the liquid separator, the gas phase was separated from the top and measured by a mass flow meter, and the liquid phase product was separated from the bottom and measured by an electronic scale. The evaluation conditions and results of each example are shown in Tables 2 and 3, where the catalyst performance was evaluated according to the following calculation method:

[0268] Isomerization activity index:

[0269] Xylene yield:

[0270] Ethylbenzene conversion rate:

[0271] Table 2

[0272]

[0273] Table 3

[0274]

[0275]

[0276] As shown in Tables 2 and 3, the bifunctional catalyst disclosed in the present invention is used for C 8 Aromatic isomerization reaction, ethylbenzene conversion rate is high, C 8 The yield is high and the reaction stability is good; further, according to the comparison of the data of Examples 3 and 6, it can be seen that when the content of the Pt element in the molecular sieve is in the preferred range of 0.05-1.5 weight%, the amount of precious metal can be reduced while ensuring the catalytic performance; according to the comparison of the data of Examples 3 and 7, it can be seen that when the content of the molecular sieve in the catalyst is in the preferred range of 10-80 weight%, the catalyst can obtain better catalytic performance.

[0277] 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.

[0278] 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.

[0279] 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 bifunctional catalyst, characterized in that: The bifunctional catalyst comprises a Pt-containing EU-1 molecular sieve and a binder component; 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; Relative to the total weight of the bifunctional catalyst, the content of the Pt-containing EU-1 molecular sieve is 5-90 wt %, and the content of the binder component is 10-95 wt %.

2. The bifunctional catalyst according to claim 1, wherein The binder component includes one or more of aluminum oxide, silicon dioxide and phosphorus pentoxide.

3. A method for preparing a bifunctional catalyst, characterized in that: The method comprises: mixing Pt-containing EU-1 molecular sieve with a binder and then performing a molding process; 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.

4. The method according to claim 3, 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.

5. The method according to claim 3, wherein: 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; The particle size of the Pt active component is less than 3 nm.

6. The method according to claim 3, wherein: The method for preparing the Pt-containing EU-1 molecular sieve 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.

7. The method according to claim 6, 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.

8. The method according to claim 6, 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.

9. The method according to claim 6, wherein: In step S1, the conditions of the first hydrothermal crystallization reaction include: time of 10-30 hours and temperature of 90-130°C.

10. The method according to claim 6, 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.

11. The method according to claim 6, 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.

12. The method according to claim 3, wherein: The binder includes one or more of SB powder, silicon dioxide and phosphorus pentoxide; The weight ratio of the Pt-containing EU-1 molecular sieve to the binder calculated as oxide is (5-90):(10-95).

13. The method according to claim 3, wherein: The method comprises the following steps: a. mixing the Pt-containing EU-1 molecular sieve, the extrusion aid, the peptizing agent and the binder, and performing the molding process to obtain a first product; b. subjecting the first product to a first drying treatment and a third heat treatment to obtain a second product; c. contacting the second product with an ion exchange liquid to perform ion exchange treatment to obtain a third product; d. subjecting the third product to a second drying treatment and a fourth heat treatment; Alternatively, the method comprises the following steps: A. contacting the Pt-containing EU-1 molecular sieve with an ion exchange liquid to perform an ion exchange treatment to obtain a fourth product; B. subjecting the fourth product to a third drying treatment and a fifth heat treatment to obtain a fifth product; C. mixing the fifth product, the extrusion aid, the peptizing agent and the binder, and performing the molding process to obtain the sixth product; D. subjecting the sixth product to a fourth drying treatment and a sixth heat treatment; Optionally, the ion exchange solution includes an acid solution or an ammonium salt solution; The acid solution includes one or more of hydrochloric acid solution, nitric acid solution and sulfuric acid solution; The ammonium salt in the ammonium salt solution includes one or more of ammonium chloride, ammonium nitrate, ammonium sulfate, ammonium carbonate and ammonium bicarbonate; The conditions of the ion exchange treatment include: time of 0.5-6h, temperature of 60-100°C; Optionally, the conditions of the first drying treatment, the second drying treatment, the third drying treatment and the fourth drying treatment are the same or different, and respectively include: a time of 80-120° C., a time of 1-10 h; Optionally, the conditions of the third heat treatment, the fourth heat treatment, the fifth heat treatment and the sixth heat treatment are the same or different, and respectively include: time of 2-10h, temperature of 500-600°C.

14. The method according to claim 13, wherein: Step a comprises: treating the Pt-containing EU-1 molecular sieve at 400-540° C. for 2-6 hours under a hydrogen atmosphere, and then performing the molding treatment; Optionally, step A comprises: treating the Pt-containing EU-1 molecular sieve at 400-540° C. for 2-6 hours under a hydrogen atmosphere, and then performing the ion exchange treatment.

15. A bifunctional catalyst prepared by the method according to any one of claims 3 to 14.

16. A method for isomerization of C8 aromatics, the method comprising: In the presence of a catalyst, the C8 aromatic hydrocarbon is contacted with hydrogen and reacted, wherein the catalyst comprises the bifunctional catalyst described in any one of claims 1, 2 and 15.

17. The method according to claim 16, wherein: The method further comprises: before carrying out the reaction, contacting the bifunctional catalyst with a hydrogen atmosphere for reduction treatment; The reduction treatment conditions include: time of 0.5-10h and temperature of 250-600°C.

18. The method according to claim 16, wherein: The reaction conditions include: a temperature of 300-500°C, a pressure of 0.3-1.5 MPa, a molar ratio of hydrogen to C8 aromatic hydrocarbons of (1-10):1, and a feed mass space velocity of 1-10 h -1 .

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