CN119819357A - Dual-function catalyst and preparation method and application thereof - Google Patents
Dual-function catalyst and preparation method and application thereof Download PDFInfo
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Abstract
本公开涉及一种双功能催化剂及其制备方法和应用，所述双功能催化剂包括含Pt的EU‑1分子筛和粘结剂组分；所述EU‑1分子筛中含有Pt活性组分，至少部分的所述Pt活性组分封装于所述EU‑1分子筛的晶体内部；相对于所述双功能催化剂的总重量，所述含Pt的EU‑1分子筛的含量为5‑90重量％，所述粘结剂组分的含量为10‑95重量％。将上述催化剂用于C8芳烃异构化反应，具有较好的C8芳烃异构化催化活性和稳定性，并具有较高的C8芳烃收率。
The present disclosure relates to a bifunctional catalyst and 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, and at least part of the Pt active component is encapsulated in 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% by weight, and the content of the binder component is 10-95% by weight. The above catalyst is used for C8 aromatics isomerization reaction, has good C8 aromatics isomerization catalytic activity and stability, and has a high C8 aromatics yield.
Description
Technical Field
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
Zeolite molecular sieve is a functional material with unique structure and property, and has been widely used in petrochemical industry, fine chemical industry, environmental protection and other fields.
The EUO type molecular sieve has a one-dimensional pore network structure with a pore diameter of 0.41×0.57 nm, and the one-dimensional pore channels also have side pockets with a depth of 0.81 nm and a diameter of 0.68×0.58 nm.
US4537754 discloses an EU-1 type molecular sieve and a method of synthesizing the same. The preparation method comprises the steps of taking an alkylated derivative of polymethylene alpha-omega-diamine ion or a precursor thereof as a template agent, uniformly mixing a silicon source, an aluminum source, an alkali metal compound, the template agent and water, and performing hydrothermal crystallization to obtain the template agent precursor. The molar ratio of SiO 2/Al2O3 of the synthesized EU-1 type molecular sieve is 10-500.
CN1327946a discloses a process for preparing zeolite of structure type EUO, the zeolite obtained and its use. In the method, EUO zeolite seed crystal is used in the presence of benzhydryl dimethyl ammonium salt and nitrogen-containing organic structural agent Q of a precursor corresponding to the salt to synthesize an EUO type molecular sieve with the SiO 2/Al2O3 mol ratio of 10-100, and the molecular sieve can be used for aromatic hydrocarbon isomerization reaction and can reduce net loss caused by side reaction.
CN99126910.1 reports EUO zeolite containing crystals and crystalline aggregates with specific particle distribution and its use as catalyst for isomerising C 8 aromatic hydrocarbons. The patent uses alkylated polymethylene alpha-omega-diamine ion as a template agent, and controls the reaction temperature and different stirring rates to ensure that the particle distribution Dv of zeolite aggregates is less than or equal to 500 mu m, and the zeolite aggregates have relatively high ethylbenzene conversion rate when used for C 8 arene isomerization.
Disclosure of Invention
The purpose of the present disclosure is to provide a bifunctional catalyst, a preparation method and an application thereof, wherein the bifunctional catalyst is used for a C 8 arene isomerization reaction, has good C 8 arene isomerization catalytic activity and stability, and has high C 8 arene yield.
To achieve the above object, a first aspect of the present disclosure provides a bifunctional catalyst comprising 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 crystals of the EU-1 molecular sieve;
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%, relative to the total weight of the bifunctional catalyst.
Optionally, the binder component comprises one or more of aluminum oxide, silicon dioxide, and phosphorus pentoxide.
A second aspect of the present disclosure provides a method of preparing a bifunctional catalyst, the method comprising mixing a Pt-containing EU-1 molecular sieve with a binder, and then performing a shaping process;
The EU-1 molecular sieve contains a Pt active component, and at least part of the Pt active component is encapsulated in crystals of the EU-1 molecular sieve.
Optionally, the relative crystallinity of the EU-1 molecular sieve containing Pt is more than 90%, the pore volume is 0.2-0.4cm 3/g, the specific surface area is 390-430m 2/g, and the silicon-aluminum ratio is 20-300.
Alternatively, the content of Pt element is 0.03-2 wt%, preferably 0.05-1.5 wt%, based on the total weight of the Pt-containing EU-1 molecular sieve;
the Pt active component has a particle size of 3nm or less.
Optionally, the method for preparing the EU-1 molecular sieve comprising Pt comprises the steps of:
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 guiding agent;
s2, carrying out contact reaction on a platinum source, a molecular sieve raw material and water, and carrying out first heat treatment on the obtained solid product to obtain a first material;
S3, contacting the first material, the optional second silicon source, the optional second aluminum source, the second alkali source, the guiding agent and water, performing a second hydrothermal crystallization reaction on the obtained mixture, and performing second heat treatment on a solid product obtained by the second hydrothermal crystallization reaction.
Optionally, the first silicon source and the second silicon source are the same or different and each independently comprise one or more of amorphous aluminum silicate, silicon aluminum spheres, 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 respectively and independently comprise one or more of amorphous aluminum silicate, silicon aluminum 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 respectively and independently comprise one or more of NaOH, liOH and KOH;
the platinum source comprises tetraammine platinum chloride;
The template agent comprises one or more of benzhydryl dimethyl ammonium salt, alkylated polymethylene alpha-omega diammonium salt, a precursor of benzhydryl dimethyl ammonium salt and a precursor of alkylated polymethylene alpha-omega diammonium salt;
The molecular sieve raw material comprises a molecular sieve with the aperture of more than 0.6nm, and preferably comprises one or more of an X molecular sieve, a Y molecular sieve, a beta molecular sieve and a mercerized molecular sieve.
Optionally, in step S1, the molar ratio of the template, the first alkali source calculated as metal oxide, the first aluminum source calculated as Al 2O3, water, and the first silicon source calculated as SiO 2 is (0.1-0.7): 0.05-0.3): 0.003-0.05): 10-100): 1;
in the step S2, the weight ratio of the platinum source to the molecular sieve raw material calculated by Pt element 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 the step S3, the mole ratio of alkali metal element calculated as metal oxide, aluminum element calculated as Al 2O3, water and silicon element calculated as SiO 2 in the mixture is (0.1-0.3): (0.005-0.05): (10-100): 1;
The weight ratio of the guiding agent to the silicon element in the mixture calculated as SiO 2 is (0.5-5): 1.
Optionally, in the step S1, the conditions of the first hydrothermal crystallization reaction comprise the time of 10-30h and the temperature of 90-130 ℃.
Optionally, in the step S2, the conditions of the contact reaction comprise the time of 0.4-2h and the temperature of 80-100 ℃;
the conditions of the first heat treatment comprise a time of 2-6h and a temperature of 450-550 ℃.
Optionally, in the step S3, the conditions of the second hydrothermal crystallization reaction comprise 40-100h at 160-200 ℃, preferably 50-80h at 170-190 ℃;
The conditions of the second heat treatment comprise 2-12h and 500-600 ℃.
Optionally, the binder comprises one or more of SB powder, silica and phosphorus pentoxide;
the weight ratio of the EU-1 molecular sieve containing Pt to the binder calculated as oxide is (5-90): 10-95.
Optionally, the method comprises the steps of:
a. Mixing the EU-1 molecular sieve containing Pt, an extrusion aid and a peptizing agent with the binder, and performing the forming treatment to obtain a first product;
b. carrying out first drying treatment and third heat treatment on the first product to obtain a second product;
c. Contacting the second product with ion exchange liquid, and performing ion exchange treatment to obtain a third product;
d. subjecting the third product to a second drying treatment and a fourth heat treatment;
Or the method comprises the following steps:
A. Contacting the EU-1 molecular sieve containing Pt with an ion exchange liquid, and performing ion exchange treatment to obtain a fourth product;
B. carrying out third drying treatment and fifth heat treatment on the fourth product to obtain a fifth product;
C. mixing the fifth product, the extrusion aid, the peptizing agent and the binder, and performing the forming treatment to obtain a sixth product;
D. subjecting the sixth product to a fourth drying treatment and a sixth heat treatment;
optionally, the ion exchange liquid comprises an acid solution or an ammonium salt solution;
the acid solution comprises one or more of hydrochloric acid solution, nitric acid solution and sulfuric acid solution;
the ammonium salt in the ammonium salt solution comprises one or more of ammonium chloride, ammonium nitrate, ammonium sulfate, ammonium carbonate and ammonium bicarbonate;
the conditions of the ion exchange treatment comprise time of 0.5-6h and temperature of 60-100 ℃;
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 the conditions respectively comprise the time of 80-120 ℃ and the time of 1-10h;
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 the conditions respectively comprise the time of 2-10h and the temperature of 500-600 ℃.
Optionally, step a comprises treating the Pt-containing EU-1 molecular sieve at 400-540 ℃ for 2-6 hours under a hydrogen atmosphere, and then performing the forming treatment;
Alternatively, step A comprises treating the Pt-containing EU-1 molecular sieve at 400-540 ℃ for 2-6 hours under a hydrogen atmosphere, and then performing the ion exchange treatment.
A third aspect of the present disclosure provides a bifunctional catalyst prepared by the method of the second aspect of the present disclosure.
A fourth aspect of the present disclosure provides a process for isomerising a C 8 aromatic hydrocarbon, the process comprising contacting and reacting the C 8 aromatic hydrocarbon with hydrogen in the presence of a catalyst comprising a bifunctional catalyst as described in the first or third aspects of the present disclosure.
Optionally, the method further comprises contacting the dual-function catalyst with a hydrogen atmosphere for a reduction treatment prior to performing the reaction;
The conditions of the reduction treatment comprise time of 0.5-10h and temperature of 250-600 ℃.
Optionally, the reaction conditions comprise a temperature of 300-500 ℃ and a pressure of 0.3-1.5MPa, the molar ratio of the hydrogen to the C 8 aromatic hydrocarbon is (1-10): 1, and the feeding mass space velocity calculated by the C 8 aromatic hydrocarbon is 1-10h -1.
According to the technical scheme, the catalyst is prepared by taking the EU-1 molecular sieve containing Pt as an acidic component and a noble metal hydrogenation dehydrogenation component, the Pt active component in the EU-1 molecular sieve containing Pt is not agglomerated, the crystallinity of the molecular sieve is high, and the prepared bifunctional catalyst is used for C 8 arene isomerization reaction, has good C 8 arene isomerization catalytic activity and stability, and has high C 8 arene yield.
Additional features and advantages of the present disclosure will be set forth in the detailed description which follows.
Drawings
The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of this specification, illustrate the disclosure and together with the description serve to explain, but do not limit the disclosure. In the drawings:
FIG. 1 is an X-ray diffraction (XRD) pattern of Pt-containing EU-1 molecular sieve A prepared in example 1 of the present disclosure.
FIG. 2 is a spherical aberration diagram of EU-1 molecular sieve A containing Pt prepared in example 1 of the present disclosure.
FIG. 3 is a transmission electron microscopic image of the catalyst D-1 prepared in comparative example 1 of the present disclosure.
Detailed Description
Specific embodiments of the present disclosure are described in detail below with reference to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating and illustrating the disclosure, are not intended to limit the disclosure.
A first aspect of the present disclosure provides a bifunctional catalyst comprising 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 crystals of the EU-1 molecular sieve;
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%, relative to the total weight of the bifunctional catalyst.
In the present disclosure, "at least a portion of the Pt active component is encapsulated within the crystals of the molecular sieve" means that a portion or all of the Pt active component is present within the crystals of the EU-1 molecular sieve, preferably all of the Pt active component is present within the crystals of the EU-1 molecular sieve.
According to one embodiment of the present disclosure, 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%, relative to the total weight of the dual-function catalyst.
According to one embodiment of the present disclosure, the binder component includes one or more of aluminum oxide, silicon dioxide, and phosphorus pentoxide.
A second aspect of the present disclosure provides a method of preparing a bifunctional catalyst, the method comprising the steps of:
Mixing an EU-1 molecular sieve containing Pt with a binder, and then performing forming treatment;
The EU-1 molecular sieve contains a Pt active component, and at least part of the Pt active component is encapsulated in crystals of the EU-1 molecular sieve.
According to one embodiment of the present disclosure, the content of Pt element is 0.03 to 2 wt%, preferably 0.05 to 1.5 wt%, based on the total weight of the EU-1 molecular sieve containing Pt, which can reduce cost while maintaining catalyst activity.
According to one embodiment of the present disclosure, the Pt active component has a particle size of 3nm or less, preferably 2nm or less, more preferably 0.5-1.5nm.
According to one embodiment of the present disclosure, the molecular sieve has a relative crystallinity of 90% or more, preferably 95% or more, and the relative crystallinity is calculated based on EU-1 molecular sieve synthesized by hydrothermal crystallization using trimethylhexamethylene diammonium bromide as a template in chinese patent application CN 99126910.1.
According to one embodiment of the present disclosure, the molecular sieve has a pore volume of 0.2 to 0.4cm 3/g, a specific surface area of 390 to 430m 2/g, a silica to alumina ratio of 20 to 300, preferably 25 to 100, wherein the silica to alumina ratio refers to the molar ratio of SiO 2 and Al 2O3 in the molecular sieve.
According to one embodiment of the present disclosure, a method of preparing a Pt-containing EU-1 molecular sieve includes the steps of:
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 guiding agent;
s2, carrying out contact reaction on a platinum source, a molecular sieve raw material and water, and carrying out first heat treatment on the obtained solid product to obtain a first material;
S3, contacting the first material, the optional second silicon source, the optional second aluminum source, the second alkali source, the guiding agent and water, performing a second hydrothermal crystallization reaction on the obtained mixture, and performing second heat treatment on a solid product obtained by the second hydrothermal crystallization reaction.
In the method, the first material is the Pt ion exchange molecular sieve, the Pt active component is encapsulated in the EU-1 molecular sieve in the crystal, the Pt active component is not agglomerated and the crystallinity of the molecular sieve is higher by carrying out hydrothermal crystallization reaction in a crystal transformation mode, and the bifunctional catalyst prepared by using the Pt active component as an acidic component and a noble metal hydrogenation dehydrogenation component is used for C 8 arene isomerization reaction, and has better C 8 arene isomerization catalytic activity and stability, higher target product selectivity and higher C 8 arene yield.
In the present disclosure, the manner of heat treatment is conventional in the art, and may be, for example, calcination.
According to one embodiment of the disclosure, the first silicon source and the second silicon source are the same or different and respectively and independently comprise one or more of amorphous aluminum silicate, silica-alumina spheres, amorphous silicon dioxide, silica sol, ethyl orthosilicate, propyl orthosilicate and butyl orthosilicate, and the first aluminum source and the second aluminum source are the same or different and respectively and independently comprise one or more of amorphous aluminum silicate, silica-alumina spheres, sodium metaaluminate, aluminum sulfate, aluminum nitrate, aluminum alkoxide, aluminum oxide, alumina sol, pseudo-boehmite and boehmite, wherein sodium metaaluminate, amorphous aluminum silicate and silica-alumina spheres can be used as the silicon source or the aluminum source.
According to one embodiment of the present disclosure, the first and second alkali sources may be, for example, inorganic alkali, preferably alkali metal hydroxide, specifically, the first and second alkali sources are the same or different and each independently include one or several of NaOH, liOH and KOH, and the platinum source includes platinum tetra-ammine chloride, but is not limited thereto.
According to one embodiment of the present disclosure, the templating agent includes one or more of a benzhydryl dimethyl ammonium salt, an alkylated polymethylene alpha-omega diammonium salt, a precursor of a benzhydryl dimethyl ammonium salt, and a precursor of an alkylated polymethylene alpha-omega diammonium salt. Wherein the precursor can be synthesized into benzhydryl dimethyl ammonium salt or alkylated polymethylene alpha-omega diammonium salt, wherein the alkylated polymethylene alpha-omega diammonium salt is preferably alkyl dibromo hexanediammonium, such as trimethyl dibromohexanediamineOr a mixture of trimethylammonium and dibromohexane, and trimethyl dibromodiammonium is generated through in-situ reaction.
According to one embodiment of the present disclosure, the molecular sieve raw material is a large pore size molecular sieve, the pore size of which is more than 0.6nm, preferably including one or more of an X molecular sieve, a Y molecular sieve, a β molecular sieve and a mercerized molecular sieve, and when the molecular sieve raw material includes two or more kinds, the ratio thereof is not particularly limited.
According to one embodiment of the present disclosure, in step S1, the molar ratio of the template, the first alkali source in terms of metal oxide, the first aluminum source in terms of Al 2O3, water, and the first silicon source in terms of SiO 2 is (0.1-0.7): (0.05-0.3): (0.003-0.05): (10-100): 1, e.g., when the first alkali source is NaOH, the amount of the first alkali source is Na 2 O.
According to one embodiment of the disclosure, in step S2, the weight ratio of the platinum source to the molecular sieve raw material calculated as Pt element is 1 (20-100), preferably 1 (22-80), and 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).
In step S3, the molar ratio of alkali metal oxide, elemental aluminum, as Al 2O3, water to elemental silicon, as SiO 2, in the mixture comprising the first feedstock, the second silicon source, the second aluminum source, the second alkali source, and the water is (0.1-0.3): (0.005-0.05): (10-100): 1.
According to one embodiment of the present disclosure, in step S3, the weight ratio of the directing agent to elemental silicon in the mixture, calculated as SiO 2, is (0.5-5): 1.
According to one embodiment of the disclosure, in the step S1, the conditions of the first hydrothermal crystallization reaction comprise the time of 10-30h and the temperature of 90-130 ℃, and the first hydrothermal crystallization reaction is carried out under the autogenous pressure of the reactor.
According to one embodiment of the present disclosure, the contacting reaction conditions in step S2 include a time of 0.5 to 2 hours and a temperature of 80 to 100 ℃, and the contacting reaction may be performed in a water bath condition in order to sufficiently proceed the reaction.
According to one embodiment of the disclosure, the step S2 further includes performing solid-liquid separation on the mixed material obtained by the contact reaction, and performing drying treatment on the obtained solid material, and then performing a first heat treatment, where the drying treatment is performed in a manner and under conditions conventional in the art, for example, the temperature may be 110-120 ℃ and the time may be 2-12 hours, and the solid-liquid separation is performed in a manner conventional in the art, for example, filtration may be performed.
According to one embodiment of the present disclosure, in the step S2, the first heat treatment condition includes a time of 2 to 6 hours and a temperature of 450 to 550 ℃.
According to one embodiment of the present disclosure, in the step S3, the conditions of the second hydrothermal crystallization reaction include a time of 40 to 100 hours and a temperature of 160 to 200 ℃, preferably a time of 50 to 80 hours and a temperature of 170 to 190 ℃.
According to one embodiment of the present disclosure, in the step S3, the conditions of the second heat treatment include a time of 2 to 12 hours and a temperature of 500 to 600 ℃.
According to one embodiment of the present disclosure, step S3 may include mixing the first material, the optional second silicon source, the optional second aluminum source, the second alkali source, and water, then mixing the resulting mixture with a directing agent, performing a second hydrothermal crystallization reaction, and subjecting the resulting solid product to a second heat treatment.
According to one embodiment of the disclosure, the step S3 further comprises performing solid-liquid separation on the mixed material obtained by the second hydrothermal crystallization reaction, and then performing washing and drying treatment on the obtained solid material, and then performing second heat treatment, wherein the drying treatment mode and condition are conventional in the art, for example, the temperature can be 110-120 ℃ and the time can be 2-12h, the solid-liquid separation mode is conventional in the art, for example, filtration can be performed, and the washing method is conventional in the art.
According to one embodiment of the present disclosure, the method comprises the steps of:
a. Mixing the EU-1 molecular sieve containing Pt, an extrusion aid and a peptizing agent with the binder, and performing the forming treatment to obtain a first product;
b. carrying out first drying treatment and third heat treatment on the first product to obtain a second product;
c. Contacting the second product with ion exchange liquid, and performing ion exchange treatment to obtain a third product;
d. and carrying out second drying treatment and fourth heat treatment on the third product.
According to one embodiment of the present disclosure, the method comprises the steps of:
A. Contacting the EU-1 molecular sieve containing Pt with an ion exchange liquid, and performing ion exchange treatment to obtain a fourth product;
B. carrying out third drying treatment and fifth heat treatment on the fourth product to obtain a fifth product;
C. mixing the fifth product, the extrusion aid, the peptizing agent and the binder, and performing the forming treatment to obtain a sixth product;
D. And carrying out fourth drying treatment and sixth heat treatment on the sixth product.
According to one embodiment of the present disclosure, the mass ratio of the Pt-containing EU-1 molecular sieve to the binder in terms of oxide is (5-90): (10-95), preferably (10-80): (20-90).
According to one embodiment of the present disclosure, the binder includes one or more of SB powder, silica, and phosphorus pentoxide.
According to one embodiment of the present disclosure, the ion exchange treatment is performed under continuous agitation, and the conditions include a time of 0.5 to 6 hours, a temperature of 60 to 100 ℃, and a liquid-to-solid weight ratio of the ion exchange liquid to the molecular sieve or the second product of (1 to 10): 1, and the ion exchange treatment may be repeated several times, for example, may be performed twice.
According to one embodiment of the disclosure, the ion exchange liquid comprises an acid solution or an ammonium salt solution, wherein when the ion exchange liquid is an acid solution, the concentration of the acid solution is 1-10 wt%, when the ion exchange liquid is an ammonium salt solution, the concentration of the ammonium salt solution is 1-10 wt%, the acid solution comprises one or more of a hydrochloric acid solution, a nitric acid solution and a sulfuric acid solution, and the ammonium salt in the ammonium salt solution comprises one or more of ammonium chloride, ammonium nitrate, ammonium sulfate, ammonium carbonate and ammonium bicarbonate.
According to one embodiment of the present disclosure, step a comprises treating the Pt-containing EU-1 molecular sieve at 400-540 ℃ for 2-6 hours under a hydrogen atmosphere, and then performing a forming treatment.
According to one embodiment of the present disclosure, step A comprises treating the Pt-containing EU-1 molecular sieve at 400-540 ℃ for 2-6 hours under a hydrogen atmosphere, and then performing the ion exchange treatment.
According to one embodiment of the present disclosure, the conditions of the first drying process, the second drying process, the third drying process and the fourth drying process are the same or different, and each include a time of 80-120 ℃ and a time of 1-10h, preferably a temperature of 100-120 ℃ and a time of 2-6h, and the drying process is conventional in the art and will not be described herein.
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 each include a time of 2 to 10 hours, a temperature of 500 to 600 ℃, preferably a time of 3 to 5 hours, and a temperature of 500 to 550 ℃.
In the present disclosure, the molding process is conventional in the art, and may be, for example, extrusion molding, tabletting molding, drop ball molding, spray molding or roll molding, preferably extrusion molding, specifically, step a includes mixing molecular sieve, binder, extrusion aid and peptizing agent, and then performing molding, the extrusion aid is used in an amount of 0.5 to 5% by weight relative to the total weight of the molecular sieve and binder, step C includes mixing fifth product, extrusion aid, peptizing agent and binder, the extrusion aid is used in an amount of 0.5 to 5% by weight relative to the total weight of the fifth product and binder, the extrusion aid may include one or more of sesbania powder, starch and methylcellulose, the peptizing agent includes one or more of dilute nitric acid, oxalic acid, citric acid and tartaric acid, the nitric acid is preferably 1 to 8% by volume, and the remaining acid concentration is preferably 1 to 5% by volume, and the peptizing agent is conventional in the art.
A third aspect of the present disclosure provides a bifunctional catalyst prepared by the method of the second aspect of the present disclosure.
The above-mentioned bifunctional catalyst has the same features as the bifunctional catalyst described in the first aspect of the present disclosure, and will not be described here.
A fourth aspect of the present disclosure provides a process for isomerising a C 8 aromatic hydrocarbon, the process comprising contacting and reacting the C 8 aromatic hydrocarbon with hydrogen in the presence of a catalyst comprising a bifunctional catalyst as described in the first or third aspects of the present disclosure.
According to one embodiment of the present disclosure, the method further comprises contacting the bifunctional catalyst with hydrogen for a reduction treatment prior to the reaction, the conditions of the reduction treatment comprising a time of 0.5-10h and a temperature of 250-600 ℃, preferably 300-500 ℃.
According to one embodiment of the present disclosure, the reaction conditions include a temperature of 300-500 ℃, preferably 350-420 ℃, a pressure of 0.3-1.5MPa, preferably 0.4-1.0MPa, a molar ratio of the hydrogen to the C 8 aromatics (hydrogen/hydrocarbon ratio) of (1-10): 1, preferably (2-8): 1, and a feed mass space velocity of 1-10h -1, preferably 2-6h -1, calculated as C 8 aromatics.
The present disclosure will be further illustrated by the following examples, but the disclosure is not limited thereto, and the apparatus and reagents used in the examples of the present disclosure, unless otherwise indicated, are those commonly used by those skilled in the art.
XRD test conditions and instrument model the molecular sieve phase was measured by X-ray diffractometer (XRD) from PANalytical company, tube voltage 40kV, tube current 40mA, cu target K alpha ray, scan range 2 theta = 5-50 deg.
The test condition and instrument model of the spherical aberration electron microscope are that a scanning transmission microscope (STEM) is adopted to represent the distribution position and the particle size of Pt in a sample, the adopted instrument is JEOL JEL-ARM 200F, ethanol is used to disperse and prepare a dispersion liquid containing a molecular sieve sample before the sample is tested, then the dispersion liquid is taken and dropped on a copper mesh, and the dispersion liquid is put into the instrument for testing after the ethanol volatilizes.
The method and the instrument model for testing the transmission electron microscope are that the appearance of a sample is tested on a FEI TECNAI F-20 transmission electron microscope, and the accelerating voltage is 200kV.
The chemical composition and Pt content of the molecular sieve were measured by using an X-ray fluorescence spectrometer 3013 (XRF) from Nippon electric Co.
The relative crystallinity test method is that the ratio of the sum of XRD diffraction peak intensities of the sample to the sum of diffraction peak intensities of a standard sample is 100%, and the standard sample is 100%.
Particle size test method, STEM.
The specific surface area and pore volume are tested by adopting nitrogen adsorption and desorption technology to characterize the pore structure of the sample, wherein the used instrument is Micromeritics ASAP 2420. The test condition is that the sample is subjected to vacuum degassing treatment for 12 hours under the condition of 350 ℃, and then the adsorption quantity of the sample to nitrogen under different relative pressures p/p 0 is measured under the temperature of-196 ℃ to obtain an 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 the nitrogen adsorption at p/p 0 = 0.98.
The silicon-aluminum ratio test method comprises measuring the mass content of aluminum oxide and silicon dioxide of the molecular sieve by using 3013 type X-ray fluorescence spectrometer (XRF) of Japanese electric Co., ltd, and obtaining the silicon-aluminum ratio of the molecular sieve by calculation.
The molecular sieves used in the examples and comparative examples each had a pore diameter of 0.6nm or more.
The contents of the molecular sieve and binder components in the catalyst are calculated from the composition of the feedstock.
Example 1
The bifunctional catalyst A-1 was prepared by the following steps:
(1) Preparation of directing agent D1
Adding 11.6g of amorphous silica (white carbon black) into 278.4g of water, stirring, adding 0.26g of SB powder (the content of Al 2O3 is 76 wt% produced by Sasol company, germany), 1.55g of NaOH, 36.07g of trimethyl hexamethylene diamine (the purity is 97 wt%) and stirring and mixing uniformly;
The molar ratio of template agent, naOH calculated as Na 2 O, SB powder calculated as Al 2O3, water and amorphous silica calculated as SiO 2 is 0.5:0.1:0.01:80:1;
(2) Adding 5.08g of H-beta molecular sieve with a silicon-aluminum ratio of 21.8 and 0.12g of tetra-ammine platinum chloride monohydrate into 20g of deionized water (liquid-solid ratio of 3.9:1), stirring in a water bath at 90 ℃ for reaction for 1H, filtering, and drying the solid at 120 ℃ for 2H and roasting at 500 ℃ for 4H to obtain a first material;
the weight ratio of tetrammine platinum chloride monohydrate to H-beta molecular sieve calculated by Pt element is 1:76;
(3) Preparation of Pt-containing EU-1 molecular sieves
5.08G of the first material is added into 97.28g of deionized water, 2.88g of NaOH and 20.36g of silica sol (SiO 2 mass content is 30%) are added after stirring, and the materials are uniformly mixed;
In the mixed material obtained by the above mixing, the molar ratio of the alkali metal element calculated as Na 2 O, the aluminum element calculated as Al 2O3, water and the silicon element calculated as SiO 2 is 0.2:0.02:30:1;
51.92g of a guiding agent D1 (the weight ratio of the guiding agent to silicon element (calculated by SiO 2) in the mixed material of (3) is 4.8:1) is added into the mixture, and after uniform stirring, a second hydrothermal crystallization reaction is carried out for 72h under the sealed condition at 180 ℃. Cooling to 25 ℃, filtering, fully washing the solid by deionized water, drying at 120 ℃ for 6 hours, and roasting at 550 ℃ for 10 hours to obtain an EU-1 molecular sieve A containing Pt, wherein the parameters are listed in table 1;
XRD testing was performed on molecular sieve A, and the results are shown in FIG. 1, which shows that the molecular sieve A is EU-1 molecular sieve according to the diffraction position of the peak and the relative intensity of the peak;
The molecular sieve A is subjected to a ball-difference electron microscope test, the result is shown in fig. 2, and according to fig. 2, the Pt active component is encapsulated in the crystal of the molecular sieve;
(4) Preparation of bifunctional catalysts
Uniformly mixing 5g of molecular sieve A, 7g of SB powder (the content of Al 2O3 is 76 wt% manufactured by Sasol company, germany), 0.2g of sesbania powder and 10g of dilute nitric acid solution with the concentration of 3 vol%, kneading, extruding strips and molding to obtain a first product;
The amount of sesbania powder used was 1.67% by weight relative to the total weight of molecular sieve a and SB powder;
The weight ratio of the molecular sieve A to SB powder calculated by Al 2O3 is 48.5:51.5;
Drying the first product at 120 ℃ for 4 hours and roasting the first product at 550 ℃ for 5 hours to obtain a second product;
taking 8g of the second product and 60mL of ammonium chloride aqueous solution, carrying out ion exchange treatment for 2 hours under the conditions of 95 ℃ and continuous stirring, and repeating the treatment once according to the same conditions to obtain a third product;
The 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 percent;
After the third product was thoroughly washed with deionized water, it was dried at 120℃for 6 hours and calcined at 500℃for 4 hours to give bifunctional catalyst A-1, the composition of which is shown in Table 1.
Example 2
The bifunctional catalyst B-1 was prepared by the following steps:
(1) Preparation of directing agent D2
38.67G of silica sol (SiO 2 content is 30 mass%) is added into 41.19g of water, after stirring, 1.31g of sodium metaaluminate (Al 2O3 content is 45 wt%, na 2 O content is 33 wt%), 0.22g of NaOH, 21.65g of trimethyl-di-hexanediammonium bromide (purity is 97 wt%) are added, and stirring and mixing are uniform;
The molar ratio of the template agent, naOH calculated by Na 2 O, sodium metaaluminate calculated by Al 2O3, water and silica sol calculated by SiO 2 is 0.3:0.05:0.03:20:1;
(2) Adding 2.96g of H-Y molecular sieve with a silicon-aluminum ratio of 12 and 0.24g of tetrammine platinum chloride monohydrate into 10g of deionized water (liquid-solid ratio of 3.4:1), stirring in a water bath at 90 ℃ for reaction for 1H, filtering, drying the solid at 120 ℃ for 2H, and roasting the solid at 500 ℃ for 4H to obtain a first material;
the feeding weight ratio of the tetrammine platinum chloride monohydrate to the H-Y molecular sieve calculated by Pt element is 1:22;
(3) Preparation of Pt-containing EU-1 molecular sieves
2.96G of the first material is added into 92.37g of deionized water, 2.88g of NaOH and 27.38g of silica sol (the content of SiO 2 is 30 weight percent) are added after stirring and evenly mixed;
In the mixed material obtained by the above mixing, the molar ratio of the alkali metal element calculated as Na 2 O, the aluminum element calculated as Al 2O3, water and the silicon element calculated as SiO 2 is 0.2:0.02:30:1;
12.98g of a directing agent D2 (the weight ratio of the directing agent to silicon element (calculated as SiO 2) in the mixed material of (3) is 1.2:1) is added into the mixture, and after being uniformly stirred, the second hydrothermal crystallization reaction is carried out for 78 hours under the airtight condition at 170 ℃. Cooling to 25 ℃, filtering, fully washing the solid by deionized water, drying at 120 ℃ for 4 hours, and roasting at 550 ℃ for 10 hours to obtain an EU-1 molecular sieve B containing Pt, wherein the parameters are listed in table 1;
XRD test is carried out on the molecular sieve B, so that the molecular sieve B is EU-1 molecular sieve;
as shown by the ball-difference electron microscope test of the molecular sieve B, the Pt active component is encapsulated in the crystal of the molecular sieve;
(4) Preparation of bifunctional catalysts
Uniformly mixing 8g of molecular sieve B, 15g of SB powder (the content of Al 2O3 is 76 wt% manufactured by Sasol company, germany), 1g of sesbania powder and 18g of dilute nitric acid solution with the concentration of 6 vol%, kneading, extruding strips and molding to obtain a first product;
the amount of sesbania powder used was 4.35% by weight relative to the total weight of molecular sieve B and SB powder;
The weight ratio of the molecular sieve B to SB powder calculated by Al 2O3 is 41.2:58.8;
Drying the first product at 120 ℃ for 4 hours and roasting the first product at 550 ℃ for 5 hours to obtain a second product;
taking 12g of the second product and 120mL of ammonium nitrate aqueous solution, carrying out ion exchange treatment for 2 hours under the condition of 90 ℃ and continuous stirring, and repeating the treatment once according to the same condition to obtain a third product;
The weight ratio of the ion exchange liquid to the second product is 10:1, and the concentration of ammonium nitrate in the ammonium nitrate aqueous solution is 3.37 percent;
after the third product was thoroughly washed with deionized water, it was dried at 110℃for 6 hours and calcined at 500℃for 6 hours to give bifunctional catalyst B-1, the composition of which is shown in Table 1.
Example 3
The bifunctional catalyst C-1 was prepared by the following steps:
(1) Preparation of directing agent D3
Adding 11.6g of amorphous silica (white carbon black) into 162.38g of water, stirring, adding 1.46 g of sodium metaaluminate (the content of Al 2O3 is 45 wt%, the content of Na 2 O is 33 wt%), 0.62g of NaOH and 23.30g of trimethyl-di-hexanediammonium bromide (the purity is 97 wt%), stirring and mixing uniformly, and carrying out a first hydrothermal crystallization reaction on the reaction mixture for 15h under a closed condition at 130 ℃ to prepare a directing agent D3;
The molar ratio of template agent, naOH calculated as Na 2 O, sodium metaaluminate calculated as Al 2O3, water and amorphous silica calculated as SiO 2 is 0.333:0.08:0.033:46.67:1;
(2) Adding 5.08g of H-beta molecular sieve with a silicon-aluminum ratio of 21.8 and 0.18g of tetra-ammine platinum chloride monohydrate into 10g of deionized water (liquid-solid ratio of 2:1), stirring and reacting for 1H in a water bath at 90 ℃, and roasting for 4H at 500 ℃ to obtain a first material;
The feeding weight ratio of the tetrammine platinum chloride monohydrate to the H-beta molecular sieve calculated by Pt element is 1:51;
(3) Preparation of Pt-containing EU-1 molecular sieves
5.08G of the first material was added to 151.21g of deionized water, and after stirring, 2.5g of NaOH and 5.91g of silica sol (SiO 2 content: 30% by weight) were added and mixed well;
In the mixed material obtained by the above mixing, the molar ratio of the alkali metal element calculated as Na 2 O, the aluminum element calculated as Al 2O3, water and the silicon element calculated as SiO 2 was 0.29:0.033:80:1;
12.95g of a directing agent D3 (the weight ratio of the directing agent to silicon element (calculated as SiO 2) in the mixed material of (3) is 2:1) is added into the mixture, and after being uniformly stirred, the mixture is subjected to a second hydrothermal crystallization reaction for 52 hours under the airtight condition at 190 ℃. Cooling to 25 ℃, filtering, fully washing the solid by deionized water, drying at 120 ℃ for 4 hours, and roasting at 550 ℃ for 10 hours to obtain an EU-1 molecular sieve C containing Pt, wherein the parameters are listed in table 1;
XRD test is carried out on the molecular sieve C, so that the molecular sieve C is EU-1 molecular sieve;
As shown by the ball-difference electron microscope test of the molecular sieve C, the Pt active component is encapsulated in the crystal of the molecular sieve;
(4) Preparation of bifunctional catalysts
Uniformly mixing 5g of molecular sieve C, 20g of SB powder (the content of Al 2O3 is 76 wt% manufactured by Sasol company, germany), 1g of sesbania powder and 20g of dilute nitric acid solution with the concentration of 3 vol%, kneading, extruding strips and molding to obtain a first product;
the amount of sesbania powder used was 4.0% by weight relative to the total weight of molecular sieve C and SB powder;
The weight ratio of the molecular sieve C to SB powder calculated by Al 2O3 is 24.8:75.2;
Drying the first product at 120 ℃ for 4 hours and roasting the first product at 550 ℃ for 5 hours to obtain a second product;
Taking 12g of the second product and 100mL of ammonium sulfate aqueous solution, carrying out ion exchange treatment for 2 hours under the conditions of 85 ℃ and continuous stirring, and repeating the treatment once according to the same conditions to obtain a third product;
the 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 percent;
After the third product was thoroughly washed with deionized water, it was dried at 110℃for 6 hours and calcined at 500℃for 4 hours to give a bifunctional catalyst C-1 having the composition shown in Table 1.
Example 4
Reducing the molecular sieve C prepared in example 3 at 500 ℃ for 2 hours in a hydrogen atmosphere to obtain reduced Pt-containing EU-1 molecular sieve C, uniformly mixing 5g of reduced molecular sieve C, 20g of SB powder (the content of Al 2O3 is 76% by weight produced by Sasol company, germany), 1g of sesbania powder and 20g of dilute nitric acid solution with the concentration of 3% by volume, kneading, extruding, and forming to obtain a first product;
the amount of sesbania powder used was 4.0% by weight relative to the total weight of molecular sieve C and SB powder;
The weight ratio of the reduced molecular sieve C to SB powder calculated by Al 2O3 is 24.8:75.2;
Drying the first product at 120 ℃ for 4 hours and roasting the first product at 550 ℃ for 5 hours to obtain a second product;
Taking 12g of the second product and 100mL of ammonium sulfate aqueous solution, carrying out ion exchange treatment for 2 hours under the conditions of 85 ℃ and continuous stirring, and repeating the treatment once according to the same conditions to obtain a third product;
the 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 percent;
After the third product was thoroughly washed with deionized water, it was dried at 110℃for 6 hours and calcined at 500℃for 4 hours to give a bifunctional catalyst D-1 having the composition shown in Table 1.
Example 5
Carrying out ion exchange treatment on 10 g of the molecular sieve C prepared in the example 3 and 100mL of ammonium sulfate aqueous solution for 2 hours under the condition of 85 ℃ and continuous stirring, and repeating the treatment once according to the same conditions to obtain a fourth product;
the 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 percent;
Fully washing the fourth product with deionized water, drying at 110 ℃ for 6 hours, and roasting at 500 ℃ for 4 hours to obtain a fifth product;
Uniformly mixing 5g of a fifth product, 20g of SB powder (the content of Al 2O3 is 76 wt% manufactured by Sasol company, germany), 1g of sesbania powder and 20g of dilute nitric acid solution with the concentration of 3 vol%, kneading, extruding, and molding to obtain a sixth product;
the sesbania powder was used in an amount of 4.0% by weight relative to the total weight of the fifth product and SB powder;
The weight ratio of the fifth product to SB powder calculated as Al 2O3 is 24.8:75.2;
the sixth product was dried at 120℃for 4h and calcined at 550℃for 5h to give the bifunctional catalyst E-1, the composition of which is shown in Table 1.
Example 6
The method of example 3 was used to prepare a bifunctional catalyst F-1, with the difference that molecular sieve F was prepared using the following steps:
(1) Preparation of directing agent D4
38.67G of silica sol (SiO 2 content is 30 wt%) was added to 41.19g of water, after stirring, 1.31g of sodium metaaluminate (Al 2O3 content is 45 wt%, na 2 O content is 33 wt%), 0.22g of NaOH, 21.65g of trimethyl-di-hexanedi-ammonium bromide (purity is 97 wt%) were added, and stirred and mixed uniformly;
The molar ratio of the template agent, naOH calculated by Na 2 O, sodium metaaluminate calculated by Al 2O3, water and silica sol calculated by SiO 2 is 0.3:0.05:0.03:20:1;
(2) Adding 2.96g of H-Y molecular sieve with a silicon-aluminum ratio of 12 and 0.32g of tetrammine platinum chloride monohydrate into 10g of deionized water (liquid-solid ratio of 3.4:1), stirring in a water bath at 90 ℃ for reaction for 1H, filtering, drying the solid at 120 ℃ for 2H, and roasting the solid at 500 ℃ for 4H to obtain a first material;
the feeding weight ratio of the tetrammine platinum chloride monohydrate to the H-Y molecular sieve calculated by Pt element is 1:17;
(3) Preparation of Pt-containing EU-1 molecular sieves
2.96G of the first material is added into 92.37g of deionized water, 2.88g of NaOH and 27.38g of silica sol (the content of SiO 2 is 30 weight percent) are added after stirring and evenly mixed;
In the mixed material obtained by the above mixing, the molar ratio of the alkali metal element calculated as Na 2 O, the aluminum element calculated as Al 2O3, water and the silicon element calculated as SiO 2 is 0.2:0.02:30:1;
12.98g of a directing agent D4 (the weight ratio of the directing agent to silicon element (calculated as SiO 2) in the mixed material of (3) is 1.2:1) is added into the mixture, and after being uniformly stirred, the second hydrothermal crystallization reaction is carried out for 78 hours under the airtight condition at 170 ℃. Cooling to 25 ℃, filtering, fully washing the solid by deionized water, drying at 120 ℃ for 4 hours, and roasting at 550 ℃ for 10 hours to obtain an EU-1 molecular sieve F containing Pt, wherein the parameters are listed in table 1;
XRD test is carried out on the molecular sieve F, so that the molecular sieve F is EU-1 molecular sieve;
as can be seen from the ball-difference electron microscope test of the molecular sieve F, the Pt active component is encapsulated in the crystal of the molecular sieve, and the parameters of the bifunctional catalyst F-1 are shown in Table 1.
Example 7
Preparation of bifunctional catalyst G-1 Using molecular sieve C prepared in example 3:
Uniformly mixing 2g of molecular sieve C, 25g of SB powder (the content of Al 2O3 is 76 wt% manufactured by Sasol company, germany), 1g of sesbania powder and 20g of dilute nitric acid solution with the concentration of 3 vol%, kneading, extruding strips and molding to obtain a first product;
the amount of sesbania powder used was 3.7% by weight relative to the total weight of molecular sieve C and SB powder;
The weight ratio of the molecular sieve C to SB powder calculated by Al 2O3 is 9.5:90.5;
Drying the first product at 120 ℃ for 4 hours and roasting the first product at 550 ℃ for 5 hours to obtain a second product;
Taking 12g of the second product and 100mL of ammonium sulfate aqueous solution, carrying out ion exchange treatment for 2 hours under the conditions of 85 ℃ and continuous stirring, and repeating the treatment once according to the same conditions to obtain a third product;
the 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 percent;
after the third product was thoroughly washed with deionized water, it was dried at 110℃for 6 hours and calcined at 500℃for 4 hours to give a bifunctional catalyst G-1 having the composition shown in Table 1.
Comparative example 1
Catalyst H-1 was prepared by the following procedure:
23.30g of trimethylhexamethylene diammonium bromide (97% by weight purity) was added to 130g of water, followed by 40g of silica sol (29% by weight SiO 2 content) to form a first solution;
2.10g of NaOH and 1.46g of sodium aluminate (Al 2O3 content 45 wt%, na 2 O content 33 wt%) were dissolved in 16g of water to form a second solution;
adding the second solution into the first solution under stirring, adding 16.38g of water, and fully stirring to obtain a mixture;
Crystallizing the mixture at 180 ℃ for 40 hours, cooling to 25 ℃, collecting solids, fully washing the solids with deionized water, drying the solids at 110 ℃ for 10 hours, roasting the solids at 550 ℃ for 5 hours to obtain a molecular sieve H, wherein the parameters are shown in table 1, and XRD shows that the molecular sieve H is an EU-1 molecular sieve;
(2) Preparation of the catalyst
Uniformly mixing 10g of EU-1 molecular sieve H prepared in step (1), 14g of SB powder (the content of Al 2O3 is 76 wt% manufactured by Sasol company, germany), 0.4g of sesbania powder and 20g of dilute nitric acid solution with the concentration of 3 vol%, kneading, extruding to form strips, drying at 120 ℃ for 4H, and roasting at 550 ℃ for 5H to obtain a first product;
taking 12g of a first product and 90mL of 5wt% ammonium chloride aqueous solution, carrying out ion exchange for 2 hours under the conditions of 95 ℃ and continuous stirring, and repeatedly exchanging once according to the same conditions to obtain a second product;
fully washing the second product with deionized water, drying at 120 ℃ for 6 hours, and roasting at 500 ℃ for 4 hours to obtain a third product;
11g of the third product was immersed in 10mL of a chloroplatinic acid solution having a platinum content of 3.36mg/mL at 25℃for 24 hours, dried at 120℃for 6 hours, and calcined at 500℃for 6 hours to obtain catalyst H-1 having the composition shown in Table 1.
The transmission electron microscope test was conducted on the catalyst H-1, and the result is shown in FIG. 3, and it is understood from FIG. 3 that the Pt active component in the catalyst H-1 is an agglomerate.
Comparative example 2
Catalyst I-1 was prepared by the method of example 1, except for step (2):
10.8g of amorphous silica (white carbon black) and 0.12g of tetra ammine platinum chloride monohydrate are added into 20g of deionized water, stirred in a water bath at 90 ℃ for reaction for 1h, filtered and the solid is dried at 120 ℃ for 2h and baked at 500 ℃ for 4h to obtain a first material;
As shown by the ball-difference electron microscope test of the molecular sieve I, the Pt active component is distributed outside the crystal of the molecular sieve, and the aggregation of particles is larger;
(4) Preparation of the catalyst
Uniformly mixing 5g of EU-1 molecular sieve I containing Pt, 7g of SB powder (manufactured by Sasol company of Germany, the content of Al 2O3 is 76 percent by weight), 0.2g of sesbania powder and 10g of dilute nitric acid solution with the concentration of 3 percent by volume, kneading and extruding to obtain a first product;
Drying the first product at 120 ℃ for 4 hours and roasting the first product at 550 ℃ for 5 hours to obtain a second product;
Taking 8g of the second product and 60mL of 5.0 wt% ammonium chloride aqueous solution, carrying out ion exchange for 2 hours under the condition of continuous stirring at 95 ℃, and repeatedly exchanging once according to the same condition to obtain the second product;
After the second product was thoroughly washed with deionized water, it was dried at 120℃for 6 hours and calcined at 500℃for 4 hours to give catalyst I-1, the composition of which is shown in Table 1.
TABLE 1
Test case
The following examples evaluate the C 8 aromatic isomerization performance of the catalysts.
The catalysts prepared in the above examples and comparative examples were subjected to reduction treatment at 500℃for 4 hours under a hydrogen atmosphere to obtain catalysts A-2 to I-2.
Stainless steel reactor of small reactor with continuous flow fixed bedIn this, 0.5g of catalyst was charged. The raw materials comprise 1.23 wt% of C 8 non-aromatic, 3.99 wt% of ethylbenzene, 65.56 wt% of m-xylene, 29.18 wt% of o-xylene and 0.03 wt% of p-xylene.
During evaluation, the flow speed of hydrogen is controlled by a mass flowmeter, raw materials are fed by a metering pump through a buffer tank, the raw materials and the buffer tank are mixed and enter a reactor to be contacted with a hot catalyst for reaction, a reaction product enters a liquid separating tank, a gas phase is separated from the top and metered by the mass flowmeter, and a liquid phase product is separated from the bottom and metered by an electronic scale. The evaluation conditions and results of each example are shown in tables 2 and 3, wherein the catalyst performance is evaluated according to the following calculation method:
isomerization activity index:
Xylene yield:
Ethylbenzene conversion:
TABLE 2
TABLE 3 Table 3
As can be seen from tables 2 and 3, the bifunctional catalyst of the present disclosure was used for C 8 aromatic isomerization, the ethylbenzene conversion was higher, the C 8 yield was higher, and the reaction stability was better, further, as can be seen from the comparison of the data of examples 3 and 6, when the content of Pt element in the molecular sieve was in the preferred range of 0.05 to 1.5 wt%, the amount of noble metal could be reduced while the catalytic performance was ensured, and as can be seen from the comparison of the data of examples 3 and 7, the catalyst was able to obtain better catalytic performance when the molecular sieve content in the catalyst was in the preferred range of 10 to 80 wt%.
The preferred embodiments of the present disclosure have been described in detail above with reference to the accompanying drawings, but the present disclosure is not limited to the specific details of the embodiments described above, and various simple modifications may be made to the technical solutions of the present disclosure within the scope of the technical concept of the present disclosure, and all the simple modifications belong to the protection scope of the present disclosure.
In addition, the specific features described in the above embodiments may be combined in any suitable manner without contradiction. The various possible combinations are not described further in this disclosure in order to avoid unnecessary repetition.
Moreover, any combination between the various embodiments of the present disclosure is possible as long as it does not depart from the spirit of the present disclosure, which should also be construed as the disclosure of the present disclosure.
Claims (18)
1. A bifunctional catalyst comprising 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 crystals of the EU-1 molecular sieve;
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%, relative to the total weight of the bifunctional catalyst.
2. The dual function catalyst of claim 1, wherein the binder component comprises one or more of aluminum oxide, silicon dioxide, and phosphorus pentoxide.
3. A method for preparing a bifunctional catalyst, comprising mixing an EU-1 molecular sieve containing Pt with a binder, and then performing a molding treatment;
The EU-1 molecular sieve contains a Pt active component, and at least part of the Pt active component is encapsulated in crystals of the EU-1 molecular sieve.
4. The method according to claim 3, wherein the Pt-containing EU-1 molecular sieve has a relative crystallinity of 90% or more, a pore volume of 0.2 to 0.4cm 3/g, a specific surface area of 390 to 430m 2/g, and a silica-alumina ratio of 20 to 300.
5. A process according to claim 3, wherein the content of Pt element is 0.03-2 wt%, preferably 0.05-1.5 wt%, based on the total weight of the Pt-containing EU-1 molecular sieve;
the Pt active component has a particle size of 3nm or less.
6. A process according to claim 3, wherein the process for preparing the Pt-containing EU-1 molecular sieve comprises the steps of:
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 guiding agent;
s2, carrying out contact reaction on a platinum source, a molecular sieve raw material and water, and carrying out first heat treatment on the obtained solid product to obtain a first material;
S3, contacting the first material, the optional second silicon source, the optional second aluminum source, the second alkali source, the guiding agent and water, performing a second hydrothermal crystallization reaction on the obtained mixture, and performing second heat treatment on a solid product obtained by the second hydrothermal crystallization reaction.
7. The method of claim 6, wherein the first and second silicon sources are the same or different and each independently comprise one or more of amorphous aluminum silicate, silica-alumina spheres, amorphous silica, silica sol, ethyl orthosilicate, propyl orthosilicate, and butyl orthosilicate;
The first aluminum source and the second aluminum source are the same or different and respectively and independently comprise one or more of amorphous aluminum silicate, silicon aluminum 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 respectively and independently comprise one or more of NaOH, liOH and KOH;
the platinum source comprises tetraammine platinum chloride;
The template agent comprises one or more of benzhydryl dimethyl ammonium salt, alkylated polymethylene alpha-omega diammonium salt, a precursor of benzhydryl dimethyl ammonium salt and a precursor of alkylated polymethylene alpha-omega diammonium salt;
The molecular sieve raw material comprises a molecular sieve with the aperture of more than 0.6nm, and preferably comprises one or more of an X molecular sieve, a Y molecular sieve, a beta molecular sieve and a mercerized molecular sieve.
8. The method of claim 6, wherein in step S1, the molar ratio of the template, the first alkali source in terms of metal oxide, the first aluminum source in terms of Al 2O3, water, and the first silicon source in terms of SiO 2 is (0.1-0.7): 0.05-0.3): 0.003-0.05): 10-100): 1;
in the step S2, the weight ratio of the platinum source to the molecular sieve raw material calculated by Pt element 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 the step S3, the mole ratio of alkali metal element calculated as metal oxide, aluminum element calculated as Al 2O3, water and silicon element calculated as SiO 2 in the mixture is (0.1-0.3): (0.005-0.05): (10-100): 1;
The weight ratio of the guiding agent to the silicon element in the mixture calculated as SiO 2 is (0.5-5): 1.
9. The method according to claim 6, wherein in the step S1, the condition of the first hydrothermal crystallization reaction comprises a time of 10-30 hours and a temperature of 90-130 ℃.
10. The process according to claim 6, wherein in step S2, the conditions of the contact reaction include a time of 0.4 to 2 hours and a temperature of 80 to 100 ℃;
the conditions of the first heat treatment comprise a time of 2-6h and a temperature of 450-550 ℃.
11. The method according to claim 6, wherein the conditions of the second hydrothermal crystallization reaction in step S3 include a time of 40-100 hours at 160-200 ℃, preferably a time of 50-80 hours at 170-190 ℃;
The conditions of the second heat treatment comprise 2-12h and 500-600 ℃.
12. A process according to claim 3, wherein the binder comprises one or more of SB powder, silica and phosphorus pentoxide;
the weight ratio of the EU-1 molecular sieve containing Pt to the binder calculated as oxide is (5-90): 10-95.
13. A method according to claim 3, wherein the method comprises the steps of:
a. Mixing the EU-1 molecular sieve containing Pt, an extrusion aid and a peptizing agent with the binder, and performing the forming treatment to obtain a first product;
b. carrying out first drying treatment and third heat treatment on the first product to obtain a second product;
c. Contacting the second product with ion exchange liquid, and performing ion exchange treatment to obtain a third product;
d. subjecting the third product to a second drying treatment and a fourth heat treatment;
Or the method comprises the following steps:
A. Contacting the EU-1 molecular sieve containing Pt with an ion exchange liquid, and performing ion exchange treatment to obtain a fourth product;
B. carrying out third drying treatment and fifth heat treatment on the fourth product to obtain a fifth product;
C. mixing the fifth product, the extrusion aid, the peptizing agent and the binder, and performing the forming treatment to obtain a sixth product;
D. subjecting the sixth product to a fourth drying treatment and a sixth heat treatment;
optionally, the ion exchange liquid comprises an acid solution or an ammonium salt solution;
the acid solution comprises one or more of hydrochloric acid solution, nitric acid solution and sulfuric acid solution;
the ammonium salt in the ammonium salt solution comprises one or more of ammonium chloride, ammonium nitrate, ammonium sulfate, ammonium carbonate and ammonium bicarbonate;
the conditions of the ion exchange treatment comprise time of 0.5-6h and temperature of 60-100 ℃;
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 the conditions respectively comprise the time of 80-120 ℃ and the time of 1-10h;
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 the conditions respectively comprise the time of 2-10h and the temperature of 500-600 ℃.
14. The method according to claim 13, wherein step a comprises treating the Pt-containing EU-1 molecular sieve at 400-540 ℃ under a hydrogen atmosphere for 2-6 hours, followed by the shaping treatment;
Alternatively, step A comprises treating the Pt-containing EU-1 molecular sieve at 400-540 ℃ for 2-6 hours under a hydrogen atmosphere, and then performing the ion exchange treatment.
15. A bifunctional catalyst prepared by the method of any one of claims 3-14.
16. A process for isomerising a C 8 aromatic hydrocarbon comprising contacting and reacting said C 8 aromatic hydrocarbon with hydrogen in the presence of a catalyst, wherein said catalyst comprises a bifunctional catalyst as claimed in any one of claims 1, 2 and 15.
17. The method of claim 16, further comprising contacting the dual function catalyst with a hydrogen atmosphere prior to performing the reaction, and performing a reduction treatment;
The conditions of the reduction treatment comprise time of 0.5-10h and temperature of 250-600 ℃.
18. The process of claim 16 wherein the reaction conditions include a temperature of 300-500 ℃ and a pressure of 0.3-1.5MPa, a molar ratio of the hydrogen to the C 8 aromatic hydrocarbon of (1-10): 1, and a feed mass space velocity of 1-10h -1 based on the C 8 aromatic hydrocarbon.
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