A bifunctional catalyst, its preparation method and use

Abstract

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

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of catalyst preparation, in particular, to a bifunctional catalyst and a preparation method and application thereof. BACKGROUND

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

[0003] EUO type molecular sieve has one-dimensional pore network structure, and the pore size thereof is 0.41*0.57 nm. The one-dimensional pore channel also has a side pocket with a depth of 0.81 nm and a diameter of 0.68*0.58 nm.

[0004] US4537754 discloses a EU-1 type molecular sieve and a synthesis method thereof. An alkylated derivative or a precursor thereof of a poly-methylene alpha-omega-diamine ion is used as a template agent, and a silicon source, an aluminum source, an alkali metal compound, the template agent and water are uniformly mixed, and then hydrothermal crystallization is performed to obtain the EU-1 type molecular sieve. The template agent 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] CN1327946A discloses a preparation method of a zeolite of EUO structure type, the obtained zeolite and the application thereof. The method synthesizes an EUO type molecular sieve with a SiO2 / Al2O3 molar ratio of 10-100 in the presence of a diphenylmethyl dimethyl ammonium salt and a nitrogen-containing organic structure agent Q corresponding to the salt, and using EUO zeolite seeds. The molecular sieve can be used for aromatic isomerization reaction, and can reduce the net loss caused by side reactions.

[0006] CN99126910.1 reports an EUO zeolite containing crystals and crystal aggregates with a specific particle distribution and the application thereof as a catalyst for isomerization of C8 aromatic hydrocarbons. The patent uses an alkylated poly-methylene alpha-omega-diamine ion as a template agent, and controls the reaction temperature and different stirring rates to make the particle distribution Dv,90 value of the zeolite aggregate less than or equal to 500 μm, which is used for C8 aromatic isomerization and has a relatively high ethylbenzene conversion rate. SUMMARY

[0007] The purpose of the present disclosure is to provide a bifunctional catalyst and a preparation method and application thereof. The bifunctional catalyst is used for C8 aromatic isomerization reaction, has good C8 aromatic isomerization catalytic activity and stability, and has a high C8 aromatic yield.

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

[0009] The EU-1 molecular sieve contains a Pt active component, and at least a portion of the Pt active component is encapsulated inside the crystals 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] A 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 crystals 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, with a specific surface area of ​​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 wt %, preferably 0.05-1.5 wt %;

[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 to react, 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, aluminum silicate balls, sodium metaaluminate, aluminum sulfate, aluminum nitrate, aluminum alkoxide, 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 dibenzyldimethylammonium salt, alkylated polymethylene α-ω diammonium salt, a precursor of dibenzyldimethylammonium 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 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;

[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 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;

[0030] The weight ratio of the directing agent to the silicon element in the mixture calculated as SiO2 is (0.5-5):1.

[0031] Optionally, in step S1, the conditions of the first hydrothermal crystallization reaction include: time of 10-30 hours, 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 process and a sixth heat treatment;

[0048] Optionally, the ion exchange fluid comprises 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. and 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 2-10 hours, 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 method for isomerization reaction of C8 aromatics, which comprises: contacting the C8 aromatics with hydrogen and reacting them in the presence of a catalyst, wherein the catalyst comprises 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 0.5-10 hours 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, a molar ratio of hydrogen to C8 aromatic hydrocarbons of (1-10):1, and a feed mass space velocity of 1-10 h -1 .

[0061] Through the above technical solution, the catalyst disclosed in the present invention uses Pt-containing EU-1 molecular sieve as an acidic component and a precious metal hydrodehydrogenation component to prepare a bifunctional catalyst. The Pt active component in the above Pt-containing EU-1 molecular sieve does not agglomerate, and the molecular sieve has a high degree of crystallinity. The prepared bifunctional catalyst is used for the isomerization reaction of C8 aromatics, has good C8 aromatics isomerization catalytic activity and stability, and has a high C8 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 detailed description, 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 following describes the specific embodiments of the present disclosure in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present disclosure and are not intended to limit the present disclosure.

[0068] A first aspect of the present disclosure provides a 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 a portion of the Pt active component is encapsulated inside the crystals 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 crystals 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 wt%, preferably 0.05-1.5 wt%. The above content can reduce costs while maintaining catalyst activity.

[0078] According to one embodiment of the present disclosure, the particle size of the Pt active component is 3 nm or less, preferably 2 nm or less, 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 greater than 90%, preferably greater than 95%. 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.

[0080] According to one embodiment of the present disclosure, the pore volume of the molecular sieve is 0.2-0.4 cm 3 / g, with a specific surface area of ​​390-430m 2 / g, the silicon-aluminum ratio is 20-300, preferably 25-100; wherein the silicon-aluminum ratio refers to the molar ratio of SiO2 and Al2O3 in the molecular sieve.

[0081] According to one embodiment of the present disclosure, a method for preparing a 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 to react, 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 crystal rotation 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 crystallinity of the molecular sieve is also high; the bifunctional catalyst prepared by using it as an acidic component and a precious metal hydrodehydrogenation component is used for the C8 aromatics isomerization reaction, and has good C8 aromatics isomerization catalytic activity and stability, as well as high target product selectivity and a high C8 aromatics yield.

[0086] In the present disclosure, the heat treatment method is conventional in the art, for example, it can 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 comprises one or more of dibenzyldimethylammonium salt, alkylated polymethylene α-ω diammonium salt, a precursor of dibenzyldimethylammonium salt, and a precursor of alkylated polymethylene α-ω diammonium salt. The precursor is a compound that can synthesize dibenzyldimethylammonium salt or alkylated polymethylene α-ω diammonium salt; the alkylated polymethylene α-ω diammonium salt is preferably alkyl dibromohexane diammonium, for example, trimethyl dibromohexane diamine It can also be a mixture of trimethylammonium and dibromide, which is reacted in situ to generate trimethyldibromide hexane.

[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 materials include two or more, there is no specific limitation on their ratio.

[0091] 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.

[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 one embodiment of the present disclosure, in step S3, in the mixture comprising the first material, the second silicon source, the second aluminum source, the second alkali source and the water, 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.

[0094] According to one embodiment of the present disclosure, in step S3, the weight ratio of the directing agent to the silicon element in the mixture calculated as SiO2 is (0.5-5):1.

[0095] According to one 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 above-mentioned 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 one 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 one embodiment of the present disclosure, 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.

[0100] According to one embodiment of the present disclosure, in step S3, the conditions of the second heat treatment include: time of 2-12 hours, temperature of 500-600°C.

[0101] According to one embodiment of the present disclosure, step S3 may include: mixing the 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 subjecting the obtained solid product to a second heat treatment.

[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 includes 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 includes 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: a time of 0.5-6 hours, a temperature of 60-100°C, and a liquid-solid weight ratio of the ion exchange liquid to the molecular sieve or the second product of (1-10):1; the ion exchange treatment can be repeated multiple times, for example, 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 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.

[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 of 80-120°C, time of 1-10h; preferably, temperature of 100-120°C, time of 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℃; preferably, time is 3-5h, temperature is 500-550℃.

[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 the molecular sieve, the binder, the extrusion aid and the peptizing agent, and then performing a molding process, and the amount of the extrusion aid is 0.5-5 weight% relative to the total weight of the molecular sieve and the binder; step C includes: mixing the fifth product, the extrusion aid, the peptizing agent and the binder, and performing a molding process, and the amount of the extrusion aid is 0.5-5 weight% relative to the total weight of the fifth product and the binder; the extrusion aid can include one or more of 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 volume%, and the concentration of the remaining acids is preferably 1-5 volume%; the amount of the 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, and will not be described in detail here.

[0124] The fourth aspect of the present disclosure provides a method for isomerization reaction of C8 aromatics, which comprises: contacting the C8 aromatics with hydrogen and reacting them in the presence of a catalyst, wherein the catalyst comprises 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 reduction treatment conditions 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 0.3-1.5 MPa, preferably 0.4-1.0 MPa; a molar ratio of hydrogen to C8 aromatics (hydrogen / hydrocarbon ratio) of (1-10):1, preferably (2-8):1; a feed mass space velocity of 1-10 h / min based on C8 aromatics; -1 , preferably 2-6h -1 .

[0127] The present disclosure will be further illustrated below by way of examples, but the present disclosure is not limited thereby. Unless otherwise specified, the instruments and reagents used in the examples of the present disclosure are commonly used by those skilled in the art.

[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] Spherical aberration electron microscopy test conditions and instrument model: 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 test, a dispersion containing the molecular sieve sample was prepared by dispersing it with ethanol. The dispersion was then dropped onto a copper mesh. After the ethanol evaporated, the mesh was placed in the instrument for testing.

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

[0131] Test method for the content of Pt active component: 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.

[0132] The test method of relative crystallinity is: 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%, where the standard sample is 100%.

[0133] Particle size testing method: STEM.

[0134] Specific Surface Area and Pore Volume Testing Method and Conditions: The pore structure of the samples was characterized using nitrogen adsorption-desorption technology using a Micromeritics ASAP 2420 instrument. The samples were vacuum degassed at 350°C for 12 hours. The nitrogen adsorption capacity of the samples at different relative pressures (p / p0) was then measured at -196°C to generate adsorption-desorption isotherms. The specific surface area of ​​the samples was calculated using the Brunauer-Emmett-Teller (BET) equation, and the total pore volume was calculated based on the nitrogen adsorption at p / p0 = 0.98.

[0135] Testing method for silicon-aluminum ratio: The mass contents of aluminum oxide and silicon dioxide in the molecular sieve were determined using a 3013 X-ray fluorescence spectrometer (XRF) produced by Rigaku Corporation of Japan, and the silicon-aluminum ratio of the molecular sieve was 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 silica (white carbon black) was added to 278.4 g of water, stirred, and then 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 trimethylhexanediammonium dibromide (purity of 97 wt%) were added and stirred to mix thoroughly. The reaction mixture was subjected to a first hydrothermal crystallization reaction at 110° C. under sealed conditions for 18 h to prepare directing agent D1.

[0142] 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;

[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 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 the first material;

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

[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, stirred, and then 2.88 g of NaOH and 20.36 g of silica sol (SiO2 mass content 30%) were added and mixed evenly;

[0147] 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;

[0148] 51.92 g of directing agent D1 (the weight ratio of the directing agent to the weight of silicon element in the mixture (3) calculated as SiO2 is 4.8:1) was added to the above mixture, stirred evenly, and then a second hydrothermal crystallization reaction was carried out under closed conditions at 180°C for 72 hours. After cooling to 25°C, filtering, and thoroughly 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 are listed in Table 1.

[0149] The XRD test results of molecular sieve A are shown in Figure 1 According to the diffraction position and relative intensity of the peak, it can be seen that it is EU-1 molecular sieve;

[0150] The spherical aberration electron microscope test of molecular sieve A is shown in the following figure: 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, with an Al2O3 content of 76 wt%), 0.2 g of sesbania powder, and 10 g of a 3 vol% dilute nitric acid solution were mixed uniformly, kneaded, and then extruded 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] The weight ratio of molecular sieve A to SB powder calculated as Al2O3 is 48.5:51.5;

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

[0156] 8 g of the second product was treated with 60 mL of ammonium chloride aqueous solution at 95°C with continuous stirring for 2 h, and the same process was repeated once to obtain the third product.

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

[0158] The third product was thoroughly washed with deionized water, dried at 120° C. for 6 h, and calcined at 500° C. for 4 h 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 of silica sol (SiO2 content: 30% by weight) was added to 41.19 g of water, and after stirring, 1.31 g of sodium aluminate (Al2O3 content: 45% by weight, Na2O content: 33% by weight), 0.22 g of NaOH, and 21.65 g of trimethylhexanediammonium dibromide (purity: 97% by weight) were added and stirred to mix thoroughly. The reaction mixture was subjected to a first hydrothermal crystallization reaction at 120° C. under sealed conditions for 18 hours to prepare directing agent D2.

[0163] The molar ratio of the template, NaOH calculated as Na2O, sodium metaaluminate calculated as Al2O3, water and silica sol calculated as SiO2 is 0.3:0.05:0.03:20:1;

[0164] (2) 2.96 g of HY molecular sieve with a silicon-aluminum ratio of 12 and 0.24 g of tetraammine platinum chloride monohydrate were added to 10 g of deionized water (liquid-to-solid ratio 3.4:1), 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 the first material;

[0165] The weight ratio of tetraammineplatinum chloride monohydrate to HY molecular sieve calculated on the basis 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, stirred, and then 2.88 g of NaOH and 27.38 g of silica sol (SiO2 content of 30 wt%) were added and mixed evenly;

[0168] 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;

[0169] 12.98 g of directing agent D2 (the weight ratio of the directing agent to the weight of silicon element in the mixture (3) calculated as SiO2 is 1.2:1) was added to the above mixture, stirred evenly, and then a second hydrothermal crystallization reaction was carried out under closed conditions at 170°C for 78 hours. After cooling to 25°C, filtering, and thoroughly 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 are listed in Table 1.

[0170] XRD test of molecular sieve B showed that it was EU-1 molecular sieve;

[0171] The spherical aberration electron microscopy test of molecular sieve B showed that the Pt active component was encapsulated inside the crystals 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, with an Al2O3 content of 76 wt%), 1 g of sesbania powder, and 18 g of a 6 vol% dilute nitric acid solution were mixed uniformly, kneaded, and then extruded 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] The weight ratio of molecular sieve B to SB powder calculated as Al2O3 is 41.2:58.8;

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

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

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

[0179] The third product was thoroughly washed with deionized water, dried at 110°C for 6 h, and calcined at 500°C for 6 h 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 silica (white carbon black) was added to 162.38 g of water, and after stirring, 1.46 g of sodium aluminate (Al2O3 content: 45 wt %, Na2O content: 33 wt %), 0.62 g of NaOH, and 23.30 g of trimethyl hexammonium dibromide (purity: 97 wt %) were added and stirred to mix thoroughly. The reaction mixture was subjected to a first hydrothermal crystallization reaction at 130° C. under sealed conditions for 15 h to prepare directing agent D3.

[0184] The molar ratio of the template, NaOH calculated as Na2O, sodium metaaluminate calculated as Al2O3, water and amorphous silica calculated as SiO2 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-solid ratio 2:1), stirred in a 90°C water bath for 1 h, and calcined at 500°C for 4 h to obtain the first material;

[0186] The weight ratio of tetraammineplatinum chloride monohydrate to H-β molecular sieve calculated on the basis 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 (containing 30% by weight of SiO2) were added and mixed evenly;

[0189] 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;

[0190] 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 under closed conditions for 52 hours. After cooling to 25°C, filtering, and thoroughly 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 C. The parameters are listed in Table 1.

[0191] XRD test of 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 of molecular sieve C, 20 g of SB powder (produced by Sasol, Germany, with an Al2O3 content of 76 wt%), 1 g of sesbania powder, and 20 g of a 3 vol% dilute nitric acid solution were mixed uniformly, kneaded, and then extruded to obtain a first product;

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

[0196] The weight ratio of molecular sieve C to SB powder calculated as Al2O3 is 24.8:75.2;

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

[0198] 12 g of the second product was treated with 100 mL of ammonium sulfate aqueous solution at 85°C under continuous stirring for 2 h, and the same process was repeated once to obtain the 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 thoroughly washed with deionized water, dried at 110°C for 6 h, and calcined at 500°C for 4 h 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 under a hydrogen atmosphere to obtain reduced Pt-containing EU-1 molecular sieve C. 5 g of the reduced molecular sieve C, 20 g of SB powder (produced by Sasol, Germany, with an Al2O3 content of 76 wt%), 1 g of sesbania powder, and 20 g of a 3 vol% dilute nitric acid solution were mixed uniformly, kneaded, and then extruded to obtain a first product.

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

[0204] The weight ratio of reduced molecular sieve C to SB powder calculated as Al2O3 is 24.8:75.2;

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

[0206] 12 g of the second product was treated with 100 mL of ammonium sulfate aqueous solution at 85°C under continuous stirring for 2 h, and the same process was repeated once to obtain the 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 thoroughly washed with deionized water, dried at 110°C for 6 h, and calcined at 500°C for 4 h 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 subjected to ion exchange treatment with 100 mL of an aqueous ammonium sulfate solution at 85° C. with continuous stirring for 2 h, and the same treatment was 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 washed thoroughly with deionized water, dried at 110°C for 6 h, and calcined at 500°C for 4 h to obtain the fifth product;

[0213] 5 g of the fifth product, 20 g of SB powder (produced by Sasol, Germany, with an Al2O3 content of 76 wt%), 1 g of sesbania powder, and 20 g of a 3 vol% dilute nitric acid solution were mixed uniformly, kneaded, and then extruded to obtain a sixth product;

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

[0215] The weight ratio of the fifth product to the SB powder calculated as Al2O3 is 24.8:75.2;

[0216] The sixth product was dried at 120° C. for 4 h and calcined at 550° C. for 5 h 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 of silica sol (SiO2 content: 30 wt%) was added to 41.19 g of water, and after stirring, 1.31 g of sodium aluminate (Al2O3 content: 45 wt%, Na2O content: 33 wt%), 0.22 g of NaOH, and 21.65 g of trimethylhexanediammonium dibromide (purity: 97 wt%) were added and stirred to mix thoroughly. The reaction mixture was subjected to a first hydrothermal crystallization reaction at 120° C. under sealed conditions for 18 h to prepare directing agent D4.

[0221] The molar ratio of the template, NaOH calculated as Na2O, sodium metaaluminate calculated as Al2O3, water and silica sol calculated as SiO2 is 0.3:0.05:0.03:20:1;

[0222] (2) 2.96 g of HY molecular sieve with a silicon-aluminum ratio of 12 and 0.32 g of tetraammine platinum chloride monohydrate were added to 10 g of deionized water (liquid-to-solid ratio 3.4:1), 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 the first material;

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

[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, stirred, and then 2.88 g of NaOH and 27.38 g of silica sol (SiO2 content of 30 wt%) were added and mixed evenly;

[0226] 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;

[0227] 12.98 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 1.2:1) was added to the above mixture, stirred evenly, and then a second hydrothermal crystallization reaction was carried out under closed conditions at 170°C for 78 hours. After cooling to 25°C, filtering, and thoroughly 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 are listed in Table 1.

[0228] XRD test of molecular sieve F showed that it was EU-1 molecular sieve;

[0229] Spherical aberration electron microscopy test of molecular sieve F shows that the Pt active component is encapsulated inside the crystals 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] 2 g of molecular sieve C, 25 g of SB powder (produced by Sasol, Germany, with an Al2O3 content of 76% by weight), 1 g of sesbania powder, and 20 g of a 3% by volume dilute nitric acid solution were mixed uniformly, kneaded, and then extruded to obtain a first product;

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

[0234] The weight ratio of molecular sieve C to SB powder calculated as Al2O3 is 9.5:90.5;

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

[0236] 12 g of the second product was treated with 100 mL of ammonium sulfate aqueous solution at 85°C under continuous stirring for 2 h, and the same process was repeated once to obtain the 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 thoroughly washed with deionized water, dried at 110°C for 6 h, and calcined at 500°C for 4 h 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 (97 wt% purity) was added to 130 g of water, followed by 40 g of silica sol (29 wt% SiO2 content) to form a first solution;

[0242] 2.10 g of NaOH and 1.46 g of sodium aluminate (Al2O3 content of 45 wt %, Na2O content of 33 wt %) were dissolved in 16 g of water to form a second solution;

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

[0244] The above mixture was crystallized at 180°C for 40 h, cooled to 25°C, the solid was collected and washed thoroughly with deionized water, dried at 110°C for 10 h, and calcined at 550°C for 5 h 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 the EU-1 molecular sieve H prepared in step (1), 14 g of SB powder (produced by Sasol, Germany, with an Al2O3 content of 76 wt%), 0.4 g of sesbania powder and 20 g of a 3% by volume dilute nitric acid solution were mixed uniformly, kneaded and then extruded into strips, dried at 120°C for 4 h, and calcined at 550°C for 5 h to obtain the first product;

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

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

[0249] 11 g of the third product was taken and impregnated with 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 is listed in Table 1.

[0250] The catalyst H-1 was tested by transmission electron microscopy, and the results were 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 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 a first material;

[0254] Spherical aberration electron microscopy test of molecular sieve I shows that the Pt active component is distributed outside the molecular sieve crystals, 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, with an Al2O3 content of 76 wt%), 0.2 g of sesbania powder, and 10 g of a 3 vol% dilute nitric acid solution were mixed, 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 the second product;

[0258] 8 g of the second product was ion exchanged with 60 mL of a 5.0 wt% aqueous solution of ammonium chloride at 95° C. with 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 thoroughly washed with deionized water, dried at 120°C for 6 h, and calcined at 500°C for 4 h 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 C8 aromatics isomerization performance of the catalyst.

[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 reaction vessel. The raw material composition was as follows: 1.23 wt% C8 non-aromatics, 3.99 wt% ethylbenzene, 65.56 wt% m-xylene, 29.18 wt% o-xylene, and 0.03 wt% p-xylene.

[0267] During the evaluation, the hydrogen flow rate was controlled by a mass flowmeter. The raw materials were fed into the reactor via a metering pump through a buffer tank. After mixing, the two entered the reactor and reacted with the hot catalyst. The reaction products entered a separatory tank. The gas phase was separated from the top and measured by a mass flowmeter, while the liquid phase was separated from the bottom and measured by an electronic scale. The evaluation conditions and results for each example are shown in Tables 2 and 3. The catalyst performance was evaluated using 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 can be seen from Tables 2 and 3, the bifunctional catalyst disclosed herein is used for the isomerization reaction of C8 aromatics, with a high ethylbenzene conversion rate, a high C8 yield, and good reaction stability. Furthermore, according to a 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 within the preferred range of 0.05-1.5 weight %, the amount of precious metal can be reduced while ensuring the catalytic performance. According to a comparison of the data of Examples 3 and 7, when the molecular sieve content in the catalyst is within 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 of the above embodiments. Within the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all fall within the scope of protection 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. To avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0279] In addition, the 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 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 crystals of the EU-1 molecular sieve; 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 to react, 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 resulting 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; The template agent includes one or more of dibenzyldimethylammonium salt, alkylated polymethylene α-ω diammonium salt, a precursor of dibenzyldimethylammonium 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; 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.

2. The method 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, with a specific surface area of ​​390-430m 2 / g, silicon-aluminum ratio is 20-300.

3. The method 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% by weight; The particle size of the Pt active component is less than 3 nm.

4. The method 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 0.05-1.5 wt %.

5. The method according to claim 1, 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, aluminum silicate balls, sodium metaaluminate, aluminum sulfate, aluminum nitrate, aluminum alkoxide, 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 molecular sieve raw materials include one or more of X molecular sieve, Y molecular sieve, β molecular sieve and mercerized molecular sieve.

6. The method according to claim 1, wherein In step S1, the conditions of the first hydrothermal crystallization reaction include: time of 10-30 hours and temperature of 90-130°C.

7. The method according to claim 1, 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.

8. The method according to claim 1, wherein In step S3, the conditions of the second hydrothermal crystallization reaction include: time of 40-100 hours, temperature of 160-200°C; The conditions of the second heat treatment include: time of 2-12 hours and temperature of 500-600°C.

9. The method according to claim 1, wherein In step S3, the conditions of the second hydrothermal crystallization reaction include: time of 50-80 hours and temperature of 170-190°C.

10. The method according to claim 1, 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).

11. The method according to claim 1, 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 a sixth product; D. subjecting the sixth product to a fourth drying treatment and a sixth heat treatment; The conditions of the ion exchange treatment include: time of 0.5-6 hours and temperature of 60-100°C.

12. The method according to claim 11, wherein The ion exchange fluid 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.

13. The method according to claim 11, wherein: 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. and a time of 1-10 hours.

14. The method according to claim 11, wherein 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: a time of 2-10 hours and a temperature of 500-600°C.

15. The method according to claim 11, 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.

16. The method according to claim 11, 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 ion exchange treatment.

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