Aromatic hydrocarbon isomerization catalyst, preparation method therefor, and use thereof

Abstract

The present application relates to an ethylbenzene deethylation catalyst, an aromatic hydrocarbon isomerization catalyst system comprising same, preparation methods therefor, and use thereof. The ethylbenzene deethylation catalyst comprises a first molecular sieve, a first binder, a regulator, an activity inhibitor, and a first metal, and has a volume-based median pore diameter of 300-1000 nm. The first molecular sieve is lamellar; the size of the first molecular sieve crystal in the b-axis direction is 0.5-5 μm, and the sizes in the a-axis direction and the c-axis direction, which are each 2-15 μm, are larger than the size in the b-axis direction. The regulator is an inert substance having an average particle size of 5-100 μm. The activity inhibitor comprises a Si-containing substance and a C-containing substance. By means of the ethylbenzene deethylation catalyst, during aromatic hydrocarbon isomerization, the ethylbenzene conversion rate can be enhanced, and the loss of dimethylbenzene can be reduced.

Description

An aromatic hydrocarbon isomerization catalyst, its preparation method and application

[0001] Cross-reference to related applications

[0002] This application claims priority to the patent application filed by the applicant on May 28, 2024, with application number 202410673841.2 entitled "An Aromatic Hydrocarbon Isomerization Catalyst and Its Preparation Method", the contents of which are hereby incorporated herein by reference in their entirety. Technical Field

[0003] This invention relates to an aromatic hydrocarbon isomerization catalyst, its preparation method, and its applications. More specifically, this invention relates to an ethylbenzene deethylation catalyst, an aromatic hydrocarbon isomerization catalyst system comprising the same, their preparation methods, and their applications. Background Technology

[0004] In petrochemical production, C8 aromatics obtained from various processes include not only para-, meta-, and ortho-xylenes, but also ethylbenzene. Using these C8 aromatics as raw materials, para-xylene can be obtained through a combined operation including isomerization, distillation, and adsorption separation. After separating para-xylene in the adsorption separation stage, the remaining C8 aromatics mainly consist of ethylbenzene, meta-xylene, and ortho-xylene. These adsorption-separated C8 aromatics are then processed in the aromatics isomerization stage to regenerate a near-thermodynamically equilibrium mixture of xylene isomers.

[0005] Because ethylbenzene and xylene have very similar boiling points, their separation by distillation is difficult, leading to ethylbenzene accumulation in the circulating stream of the combined unit. This increases the circulating stream volume and the operational difficulty of adsorption separation, without increasing the unit's output capacity. To avoid this and improve the combined unit's production efficiency, some ethylbenzene needs to be converted and removed. Therefore, the aromatics isomerization stage typically includes an ethylbenzene conversion section and a xylene isomerization section. Currently, one route for ethylbenzene conversion is the deethylation of ethylbenzene to produce benzene. Since the boiling point difference between benzene and xylene is significant enough, they can be easily separated by distillation, effectively improving the combined unit's production efficiency.

[0006] Both the ethylbenzene conversion stage and the xylene isomerization stage typically require specific catalysts to process C8 aromatic feedstocks. However, current ethylbenzene deethylation catalysts struggle to achieve satisfactory ethylbenzene conversion and / or xylene loss rates in aromatic isomerization processes.

[0007] Therefore, an improved ethylbenzene deethylation catalyst is still needed in the aromatic isomerization process to improve the ethylbenzene conversion rate and significantly reduce xylene loss in the aromatic isomerization process. Furthermore, when used in combination with a xylene isomerization catalyst, it can simultaneously achieve improved ethylbenzene conversion rate, significantly reduced xylene loss, and good xylene isomerization activity. Summary of the Invention

[0008] The purpose of this invention is to provide an ethylbenzene deethylation catalyst, an aromatic hydrocarbon isomerization catalyst system containing it, their preparation methods, and their applications.

[0009] In a first aspect, the present invention relates to an ethylbenzene deethylation catalyst, which comprises a first molecular sieve, a first binder, a modifier, an activity inhibitor and a first metal, and has a volume median pore size of 300-1000 nm.

[0010] The first molecular sieve is plate-shaped, and the b-axis dimension of the first molecular sieve crystal is 0.5-5 μm, while at least one of the a-axis and c-axis directions has a dimension larger than that in the b-axis direction and is 2-15 μm.

[0011] The regulator is an inert substance with an average particle size of 5-100 μm, and

[0012] The active inhibitors include substances containing Si and substances containing C.

[0013] In a second aspect, the present invention relates to a method for preparing a catalyst according to the first aspect, comprising:

[0014] (1a) The first molecular sieve, the first binder precursor, the regulator and the Si-containing precursor as an activity inhibitor are mixed, an inorganic acid solution is added, and the mixture treated with inorganic acid is calcined to obtain intermediate product A-1.

[0015] (1b) Mix intermediate product A-1 with an organic ammonium solution, and then calcine the mixture in an inert atmosphere to obtain intermediate product A-2;

[0016] (1c) Immerse intermediate product A-2 in a first metal precursor solution, then remove intermediate product A-2 treated with the first metal precursor and calcine it in an inert atmosphere to obtain intermediate product A-3; and

[0017] (1d) The intermediate product A-3 was calcined in a reducing atmosphere to obtain the ethylbenzene deethylation catalyst.

[0018] Thirdly, the present invention relates to an aromatic isomerization catalyst system, comprising:

[0019] 1) According to the first aspect of the ethylbenzene deethylation catalyst, and

[0020] 2) A xylene isomerization catalyst comprising a second molecular sieve and a second binder.

[0021] Fourthly, the present invention relates to a method for preparing a catalyst system according to the third aspect, comprising:

[0022] (1) According to the preparation method of the ethylbenzene deethylation catalyst in the second aspect;

[0023] (2) The second molecular sieve and the second binder precursor are mixed, and then an inorganic acid solution is added. The mixture treated with the inorganic acid is then calcined to obtain the xylene isomerization catalyst; and

[0024] (3) The ethylbenzene deethylation catalyst and the xylene isomerization catalyst are placed separately.

[0025] Fifthly, the present invention relates to a C8 aromatic hydrocarbon isomerization method comprising contacting a reaction mixture comprising at least one of o-xylene and m-xylene and ethylbenzene with a catalyst system prepared according to the third aspect or the method described in the fourth aspect, wherein the reaction mixture is sequentially passed through the ethylbenzene deethylation catalyst and the xylene isomerization catalyst.

[0026] By utilizing specific activity inhibitors, sheet-like first molecular sieves, and a median pore size of 300-1000 nm formed by sheet-like first molecular sieves of a specific size and inert materials of a specific particle size, the ethylbenzene deethylation catalyst, when used in the C8 aromatic isomerization process, can achieve improved ethylbenzene conversion and significantly reduced xylene loss. When an aromatic isomerization catalyst system comprising the ethylbenzene deethylation catalyst and a suitable xylene isomerization catalyst is used in the C8 aromatic isomerization process, it can simultaneously achieve improved ethylbenzene conversion, significantly reduced xylene loss, and good xylene isomerization activity. Attached Figure Description

[0027] The accompanying drawings are provided to further understand this application and form part of the specification. They are used together with the following detailed description to explain this application, but do not constitute a limitation of the invention.

[0028] Figure 1 is a scanning electron microscope (SEM) photograph of the sheet-like MFI molecular sieve A prepared in Example 1 of this application.

[0029] Figure 2 is a schematic diagram of the possible positional relationship between the plate-like first molecular sieve and the regulator in the ethylbenzene deethylation catalyst of this application.

[0030] Figure 3 is a scanning electron microscope (SEM) image of the inert alumina prepared in the inert alumina preparation example of this application. Detailed Implementation

[0031] The present application will be further described in detail below through specific embodiments. It should be understood that the specific embodiments described herein are only for illustration and explanation of the present application, and do not limit the present invention in any way.

[0032] Any specific numerical values ​​disclosed herein (including the endpoints of numerical ranges) are not limited to their exact values, but should be understood to also include values ​​close to the exact value, such as all possible values ​​within ±5% of the exact value. Furthermore, with respect to the disclosed numerical ranges, one or more new numerical ranges can be obtained by arbitrarily combining the endpoint values ​​of the range, the endpoint values ​​with specific point values ​​within the range, and the specific point values ​​themselves; these new numerical ranges should also be considered as specifically disclosed herein.

[0033] Unless otherwise stated, the terms used herein have the same meaning as commonly understood by those skilled in the art, and if a term is defined herein and its definition differs from the common understanding in the art, the definition herein shall prevail.

[0034] The expressions “comprising” or “including” in this document should be interpreted as including all specifically mentioned features as well as optional, additional, or unspecified features. As used herein, the use of the term “comprising” also discloses schemes in which no other features besides the specifically mentioned features are present, such as expressions “consistently composed of” and “composed of”.

[0035] In the context of this application, the terms "one or more" and "at least one" have the same meaning and are therefore used interchangeably; the terms "one or more" and "at least one" have the same meaning and are therefore used interchangeably.

[0036] In the context of this application, the term "ethylbenzene deethylation catalyst" refers to a catalyst capable of promoting the deethylation reaction of ethylbenzene to produce benzene and optionally promoting the isomerization reaction of o-xylene and m-xylene to produce p-xylene. The term "xylene isomerization catalyst" refers to a catalyst capable of promoting the isomerization reaction of o-xylene and m-xylene to produce p-xylene and optionally promoting the deethylation reaction of ethylbenzene to produce benzene.

[0037] In the context of this application, the term "Bronsted acid" means Bronsted acid.

[0038] In the context of this application, the term "L acid" means Lewis acid.

[0039] In a first aspect, the present invention relates to an ethylbenzene deethylation catalyst, which comprises a first molecular sieve, a first binder, a modifier, an activity inhibitor and a first metal, and has a volume median pore size of 300-1000 nm.

[0040] The first molecular sieve is plate-shaped, and the b-axis dimension of the first molecular sieve crystal is 0.5-5 μm, while at least one of the a-axis and c-axis directions has a dimension larger than that in the b-axis direction and is 2-15 μm.

[0041] The regulator is an inert substance with an average particle size of 5-100 μm, and

[0042] The active inhibitors include substances containing Si and substances containing C.

[0043] According to the present invention, the term "adhesive" refers to a substance with good adhesive properties that enables materials to be tightly connected by mechanical interlocking and / or chemical bonding by forming a thin layer structure between the same or different materials.

[0044] According to the present invention, the "median volumetric pore size" is measured using mercury intrusion porosimetry. Specifically, when testing the pore structure parameters of particles using mercury intrusion porosimetry, the pressure changes during the process of allowing mercury to penetrate the particle pores; different pressures correspond to different measured pore volumes and pore sizes. The term "median volumetric pore size" refers to the pore size corresponding to half of the maximum pore volume. The median volumetric pore size can be measured using any instrument used in the chemical engineering field to measure pore structure parameters. For example, the median volumetric pore size can be measured using a MicroActive AutoPore V 9600 mercury intrusion porosimeter manufactured by Micromeritics.

[0045] According to the present invention, the term "sheet-like" has the meaning conventionally understood in the field of chemical engineering. In particular, the term "sheet-like" refers to an object having two substantially parallel surfaces, and the dimension of the distance between these two surfaces is no greater than the dimension in any other direction perpendicular to it, especially this minimum dimension being half or less of the dimension in at least one direction perpendicular to it.

[0046] According to the present invention, the ethylbenzene deethylation catalyst may have a median pore size of 300 nm, 350 nm, 400 nm, 420 nm, 450 nm, 480 nm, 500 nm, 520 nm, 550 nm, 580 nm, 600 nm, 620 nm, 650 nm, 680 nm, 700 nm, 720 nm, 750 nm, 780 nm, 800 nm, 850 nm, 900 nm, 950 nm, 1000 nm, or a range consisting of any two of the above values ​​or one of the above values ​​and one endpoint of the above range.

[0047] Preferably, the ethylbenzene deethylation catalyst has a median pore size of 350-800 nm. More preferably, the ethylbenzene deethylation catalyst has a median pore size of 400-700 nm.

[0048] According to the present invention, the dimension of the first molecular sieve in the b-axis direction can be 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1.0μm, 1.5μm, 2.0μm, 2.5μm, 3.0μm, 3.5μm, 4.0μm, 4.5μm, 5.0μm, or a dimension within a range consisting of any two of the above values ​​or one of the above values ​​and one endpoint of one of the above ranges.

[0049] Preferably, the dimension of the first molecular sieve crystal in the b-axis direction is 0.5-3 μm. More preferably, the dimension of the first molecular sieve crystal in the b-axis direction is 0.5-1 μm.

[0050] Preferably, the dimensions in both the a-axis and c-axis directions are larger than those in the b-axis direction.

[0051] According to the present invention, the dimensions in the a-axis direction and / or the c-axis direction can be 2.0 μm, 2.5 μm, 3.0 μm, 3.5 μm, 4.0 μm, 4.5 μm, 5.0 μm, 5.5 μm, 6.0 μm, 6.5 μm, 7.0 μm, 7.5 μm, 8.0 μm, 8.5 μm, 9.0 μm, 9.5 μm, 10 μm, 10.5 μm, 11 μm, 11.5 μm, 12 μm, 13 μm, 14 μm, 15 μm, or a size within a range consisting of any two of the above values ​​or one of the above values ​​and one endpoint of one of the above ranges.

[0052] Preferably, the longer of the a-axis dimension and the c-axis dimension is 2-10 μm. More preferably, the longer of the a-axis dimension and the c-axis dimension is 3-8 μm.

[0053] Preferably, at least one of the a-axis and c-axis of the first molecular sieve crystal is perpendicular to the b-axis. More preferably, the a-axis and c-axis of the first molecular sieve crystal are each independently perpendicular to the b-axis.

[0054] Preferably, the ratio of the longer of the a-axis dimension to the c-axis dimension to the b-axis dimension is greater than or equal to 3:1. More preferably, the ratio of the longer of the a-axis dimension to the c-axis dimension to the b-axis dimension is 5:1 to 50:1. Even more preferably, the ratio of the longer of the a-axis dimension to the c-axis dimension to the b-axis dimension is 5:1 to 10:1.

[0055] According to the present invention, the ratio of the longer of the a-axis dimension and the c-axis dimension to the b-axis dimension can be 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 15:1, 20:1, 30:1, 40:1, 50:1, or a range consisting of any two of the above values ​​or one of the above values ​​and one endpoint of one of the above ranges or one endpoint of one of the above ranges and one endpoint of another of the above ranges.

[0056] According to the present invention, the "average particle size" can be measured using any method and instrument commonly used in the chemical engineering field, such as sedimentation, laser, sieving, imaging, or resistance methods. Furthermore, the "average particle size" can be a linear average diameter, area average diameter, volume average diameter, weight average diameter, or specific surface area average diameter.

[0057] Preferably, the "average particle size" is the linear average diameter, which is the sum of the diameters of a certain number of particles in the sample and then divided by the total number of particles. This is equal to the arithmetic mean of the diameters of a certain number of particles in the sample, and is called the length average diameter or number average diameter.

[0058] The “average particle size” can be obtained by measuring the visual maximum size of at least 10 particles using a scanning electron microscope, and then calculating the arithmetic mean of the visual maximum sizes of these at least 10 particles.

[0059] According to the present invention, the average particle size of the regulator can be 5 μm, 10 μm, 15 μm, 18 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 27 μm, 28 μm, 29 μm, 30 μm, 31 μm, 32 μm, 33 μm, 34 μm, 35 μm, 36 μm, 37 μm, 38 μm, 39 μm, 40 μm, 41 μm, or 42 μm. 43μm, 44μm, 45μm, 46μm, 47μm, 48μm, 49μm, 50μm, 51μm, 52μm, 53μm, 54μm, 55μm, 56μm, 57μm, 58μm, 59μm, 60μm, 65μm, 70μm, 80μm, 90μm, 100μm, or a value within a range consisting of any two of the above values ​​or one of the above values ​​and one endpoint of the above range.

[0060] Preferably, the average particle size of the regulator is 10-80 μm. More preferably, the average particle size of the regulator is 20-60 μm. Even more preferably, the average particle size of the regulator is 30-50 μm.

[0061] According to the present invention, the term "inert substance" refers to a substance that does not undergo chemical reaction in strong acids (e.g., nitric acid) and strong bases (e.g., sodium hydroxide) and at high temperatures (e.g., 300 to 600°C). The inert substance is rigid. According to the present invention, the "inert substance" can be any substance that satisfies the above conditions.

[0062] Preferably, the inert substance is an inert oxide.

[0063] Preferably, the regulator is one or more selected from inert alumina, inert silica, inert titanium dioxide, and inert magnesium oxide. Since the main components of ethylbenzene deethylation catalysts typically include silica and / or alumina, the regulator is more preferably selected from inert alumina and / or inert silica to avoid introducing additional impurities. Even more preferably, the regulator is inert alumina.

[0064] In order to facilitate the overlapping arrangement of the sheet-like molecular sieve and the inert material to form a macroporous structure, the shape of the inert material can be a sphere, a quasi-sphere, an ellipsoid, and / or a quasi-ellipsoid.

[0065] The terms "sphere," "quasi-sphere," "ellipsoid," and "quasi-ellipsoid" have the conventional meanings understood in the field of chemical engineering.

[0066] The term "perfect sphere" refers to a shape in which the diameter is the same in every direction passing through the center of the sphere.

[0067] The term "quasi-sphere" refers to a sphere that is similar in shape to a perfect sphere but is not strictly a perfect sphere, whose surface also has no significant sharp edges, and whose diameter in every direction through the center of the sphere is substantially the same. Preferably, the ratio of the diameter in every direction through the center of the sphere to the maximum diameter through the center of the sphere is not less than 0.8.

[0068] The term "ellipsoid" refers to a three-dimensional geometric body formed by rotating an ellipse about its axis of symmetry, having a longest axis and multiple axes perpendicular to it. Preferably, the ratio of the length of the longest axis to the multiple axes perpendicular to it is 1:(0.5 to <1).

[0069] The term "ellipsoidal" refers to a shape similar to an ellipsoid, whose surface also lacks significant sharp edges and has a longest axis and multiple axes perpendicular to it, but the lengths of the multiple axes perpendicular to the longest axis are not exactly the same or may all be different. Preferably, the ratio of the length of the longest axis to the length of the multiple axes perpendicular to it is 1:(0.5 to <1).

[0070] The inert material can be commercially available or prepared using methods commonly used in the chemical and chemical fields, particularly in the field of catalysts. When the inert material is inert alumina, it can be obtained by calcining boehmite (preferably with an alumina content of 50 wt.% or higher) at a high temperature (e.g., 400°C).

[0071] Since the inert alumina is obtained through high-temperature treatment, it exhibits essentially no reactivity and does not deform under similar conditions for preparing catalysts containing it. Preferably, the ethylbenzene deethylation catalyst comprises 30 wt.% to 80 wt.% of a first molecular sieve, 20 wt.% to 60 wt.% of a first binder, 1 wt.% to 15 wt.% of a modifier, 1 wt.% to 18 wt.% of an activity inhibitor, and 0.01 wt.% to 0.1 wt.% of a first metal, based on the total weight of the ethylbenzene deethylation catalyst.

[0072] Preferably, the ethylbenzene deethylation catalyst comprises 45 wt.% to 70 wt.% of a first molecular sieve, based on the total weight of the ethylbenzene deethylation catalyst.

[0073] Preferably, the ethylbenzene deethylation catalyst comprises 20 wt.% to 40 wt.% of a first binder, based on the total weight of the ethylbenzene deethylation catalyst.

[0074] Preferably, the ethylbenzene deethylation catalyst contains 5 wt.% to 15 wt.% of a modifier, based on the total weight of the ethylbenzene deethylation catalyst.

[0075] Preferably, the ethylbenzene deethylation catalyst contains 5 wt.% to 15 wt.% of an activity inhibitor, based on the total weight of the ethylbenzene deethylation catalyst.

[0076] Preferably, the ethylbenzene deethylation catalyst contains 0.01 wt.% to 0.05 wt.% of a first metal, based on the total weight of the ethylbenzene deethylation catalyst.

[0077] Preferably, the ethylbenzene deethylation catalyst comprises 3.0 wt.% to 17 wt.% of the Si-containing material and 0.5 wt.% to 5.0 wt.% of the C-containing material, based on the total weight of the ethylbenzene deethylation catalyst. More preferably, the ethylbenzene deethylation catalyst comprises 3.0 wt.% to 10 wt.% of the Si-containing material, based on the total weight of the ethylbenzene deethylation catalyst. Even more preferably, the ethylbenzene deethylation catalyst comprises 1.0 wt.% to 3.0 wt.% of the C-containing material, based on the total weight of the ethylbenzene deethylation catalyst.

[0078] Preferably, the Si-containing substance is SiO2. Preferably, the C-containing substance is a roasted product of an organic ammonium, and optionally, the ethylbenzene deethylation catalyst may further contain H and / or N elements.

[0079] Preferably, the first metal is one or more selected from Pt, Pd, Ru, Ir, and Ni. More preferably, the first metal is Pt.

[0080] Preferably, the first metal exists at least partially or substantially entirely as a zero-valent element. More preferably, the first metal exists entirely as a zero-valent element.

[0081] According to the present invention, the elemental form of the first metal may be loaded onto a binder and / or a first molecular sieve. For example, a portion of the elemental form of the first metal is loaded onto the binder, and another portion of the elemental form of the first metal is loaded onto the first molecular sieve.

[0082] According to the present invention, the first molecular sieve can be monocrystalline or polycrystalline, preferably monocrystalline. Preferably, the first molecular sieve has an MFI, MEL, EUO and / or TON topology.

[0083] Preferably, the first molecular sieve has ten-membered ring channels.

[0084] Preferably, the first molecular sieve is a silica-alumina molecular sieve, wherein the molar ratio of SiO2 to Al2O3 is 30:1 to 130:1. Preferably, the molar ratio of SiO2 to Al2O3 is 40:1 to 90:1. More preferably, the molar ratio of SiO2 to Al2O3 is 45:1 to 65:1.

[0085] Preferably, the first adhesive is alumina and / or silicon dioxide. More preferably, the first adhesive is alumina.

[0086] In the ethylbenzene deethylation catalyst, the Si-containing and C-containing substances, acting as activity inhibitors, can replace the acidic H+ on the surface of the first molecular sieve. + Furthermore, the Si-containing and C-containing substances are wholly or partially bonded to the O in the Al-O on the surface of the first molecular sieve, thereby effectively inhibiting the activity of Brønsted acid and reducing the probability of xylene reaction to a certain extent, thus reducing xylene loss. When the Si-containing and C-containing substances are partially bonded to the O in the Al-O on the surface of the first molecular sieve, the other part of the Si-containing and C-containing substances may be physically adsorbed on the surface of the first molecular sieve.

[0087] Because ethylbenzene has a smaller molecular dynamic diameter than m-xylene and o-xylene molecules, ethylbenzene can enter the micropores of the first molecular sieve to react, while the entry of m-xylene and o-xylene into the micropores is restricted. When the first molecular sieve is plate-shaped, the diffusion distance of ethylbenzene and its reaction products within the micropores of the first molecular sieve can be shortened, thereby improving mass transfer performance and increasing the deethylation reactivity of ethylbenzene to a certain extent, while effectively preventing xylene from reacting and thus reducing xylene loss.

[0088] Furthermore, in the ethylbenzene deethylation catalyst of the present invention, as shown in FIG2, it is presumed that the first molecular sieve of a specific size in the form of sheets is randomly interleaved with the inert material of a specific particle size, thereby contributing to the generation of a median pore size of 300-1000 nm in the catalyst.

[0089] Compared to catalysts formed from non-plate-like molecular sieves or catalysts without inert substances, the ethylbenzene deethylation catalyst of the present invention has a much larger pore size. This large pore size of the catalyst is beneficial for increasing the diffusion rate of reactants and products, allowing reactants to quickly contact the molecular sieve, thereby accelerating the reaction and enabling products to quickly leave the catalyst, effectively avoiding side reactions. Therefore, based on the first molecular sieve being plate-like, the large pore size of this catalyst can further improve the ethylbenzene conversion rate and reduce xylene loss.

[0090] Current technologies typically employ carbonaceous pore-forming agents (such as cellulose) to create macropores during catalyst preparation. However, these agents often dissolve during high-temperature processing, resulting in unstable macropore sizes. Furthermore, carbonaceous pore-forming agents cannot achieve median pore sizes as high as 300-1000 nm. In contrast, this invention utilizes inert materials to form macropores. Because inert materials are resistant to acids, alkalis, and high temperatures, they do not undergo chemical reactions or physical deformation during catalyst preparation, thus resulting in more stable macropore sizes.

[0091] Therefore, by means of a specific activity inhibitor, a sheet-like first molecular sieve, and a pore size of 300-1000 nm formed by a sheet-like first molecular sieve of a specific size and an inert material of a specific particle size, the ethylbenzene deethylation catalyst of the present invention can achieve improved ethylbenzene conversion and significantly reduced xylene loss in the aromatic hydrocarbon isomerization process.

[0092] In a second aspect, the present invention provides a method for preparing a catalyst according to the first aspect, comprising:

[0093] (1a) The first molecular sieve, the first binder precursor, the regulator and the Si-containing precursor as an activity inhibitor are mixed, an inorganic acid solution is added, and the mixture treated with inorganic acid is calcined to obtain intermediate product A-1.

[0094] (1b) Mix intermediate product A-1 with an organic ammonium solution, and then calcine the mixture in an inert atmosphere to obtain intermediate product A-2;

[0095] (1c) Immerse intermediate product A-2 in a first metal precursor solution, then remove intermediate product A-2 treated with the first metal precursor and calcine it in an inert atmosphere to obtain intermediate product A-3; and

[0096] (1d) The intermediate product A-3 was calcined in a reducing atmosphere to obtain the ethylbenzene deethylation catalyst.

[0097] By adding a Si-containing precursor in step (1a), some acidic sites on the surface of the ethylbenzene deethylation catalyst can be passivated by the Si-containing substance. By adding an organic ammonium solution in step (1b), residual acidic sites in the ethylbenzene deethylation catalyst can be directionally coked, thereby further eliminating acidic sites on the outer surface of the catalyst by the formed C-containing substance. In step (1c), by mixing the first metal precursor solution with intermediate product A-2 and calcining it, the surface of the resulting catalyst is loaded with metal oxides; then, the reduction reaction in step (1d) converts the metal oxides loaded on the catalyst surface into elemental metals.

[0098] In step (1a), the first binder precursor is partially dissolved after mixing with the inorganic acid solution, and a binder is generated after the calcination step, thereby tightly connecting the various substances through mechanical interlocking and / or chemical bonding. Preferably, the inorganic acid solution is selected from one or more of dilute nitric acid, dilute sulfuric acid, and dilute hydrochloric acid.

[0099] According to the present invention, the preparation method of the first molecular sieve used in step (1a) may include: (i) mixing silica sol, aluminum salt solution, template agent, inorganic base, sodium fluoride and water uniformly, (ii) dynamically crystallizing the resulting mixture, and (iii) washing, drying and calcining the crystallized product to obtain the first molecular sieve.

[0100] The term "silica sol" refers to a dispersion of silica particles in water or a solvent. The SiO2 in silica sol typically contains a large amount of water and hydroxyl groups, and can therefore be represented as SiO2·nH2O. The silica sol can be commercially available or prepared using any conventional means in the field of silica sol. Preferably, the aluminum salt is one or more of aluminum sulfate, aluminum nitrate, and aluminum chloride. Preferably, the template agent is tetrapropylammonium hydroxide. Preferably, the inorganic base is sodium hydroxide and / or potassium hydroxide.

[0101] The "dynamic crystallization" can be carried out using any method and instrument commonly used in the relevant field. Preferably, the dynamic crystallization is carried out at a temperature of 150°C to 200°C for 30 to 50 hours, the drying is carried out at a temperature of 110°C to 130°C, and / or the calcination is carried out at a temperature of 500°C to 600°C for 2 to 6 hours.

[0102] According to the present invention, the regulator used in step (1a) is substantially anhydrous. Preferably, the water content of the regulator used in step (1a) is 0% to 5%.

[0103] According to the present invention, the "moisture content" can be measured using any method commonly used in the chemical industry, especially in the field of catalysts. For example, the substance to be measured is calcined at 600°C for a period of time, such as 2 to 8 hours, and its weight is recorded as m1, which is set as having a moisture content of 0 wt.%. The weight of the uncalcined substance to be measured is recorded as m2, and the moisture content is (m2-m1) / m2.

[0104] Preferably, in step (1a), the Si-containing precursor molecule has one silicon atom and the Si-containing precursor is selected from silanes and / or silicates. Preferably, the silane is one or more selected from dichlorodimethylsilane, phenyltrimethoxysilane, phenyltriethoxysilane, γ-aminopropyltriethoxysilane, and methyltriethoxysilane. Preferably, the silicate is methyl silicate and / or ethyl silicate.

[0105] Preferably, in step (1a), the weight ratio of the first molecular sieve, the first binder precursor, the Si-containing precursor and the regulator is (1.0-10):(0.5-8.0):1.0:(0.1-1.0).

[0106] Preferably, in step (1a), the first binder precursor is hydroxyl-containing and / or water-containing alumina, preferably one or more of boehmite, aluminum hydroxide and aluminum sol, more preferably boehmite.

[0107] Preferably, in step (1a), a shaping step is included before the calcination step. More preferably, in step (1a), a drying step is included between the shaping and calcination steps. Even more preferably, the mixing described in step (1a) is carried out at 50°C to 100°C, preferably 50°C to 80°C, for 2 hours to 24 hours, preferably 6 hours to 24 hours; the drying is carried out at 80°C to 120°C; and / or the calcination is carried out in an air atmosphere at 500°C to 600°C for 2 hours to 6 hours.

[0108] Preferably, in step (1b), the weight ratio of the intermediate product A-1 to the organic ammonium in the organic ammonium solution is (5-30):1. Preferably, the organic ammonium is a quaternary ammonium base and / or a quaternary ammonium salt, and has 16 or more carbon atoms. More preferably, the organic ammonium is one or more selected from tetrabutylammonium hydroxide, tetrabutylammonium bromide, and tetrapentylammonium hydroxide.

[0109] Preferably, in step (1b), after mixing intermediate product A-1 with the organic ammonium solution, a settling step is further included, thereby allowing at least a portion of the organic ammonium to be adsorbed onto intermediate product A-1. Furthermore, step (1b) generates a solid-phase carbon-containing substance after calcination, and the catalyst may optionally further contain nitrogen and / or hydrogen elements. More preferably, in step (1b), a drying step is included between the settling and calcination steps. Even more preferably, the settling in step (1b) is carried out at 20°C to 60°C, preferably 40°C to 60°C, for 20 to 60 minutes, preferably 20 to 40 minutes; the drying is carried out at 80°C to 120°C; and the calcination is carried out in a nitrogen atmosphere at 400°C to 500°C for 4 to 8 hours.

[0110] Preferably, in step (1c), the first metal precursor solution is an aqueous solution of a complex of the first metal, preferably an aqueous solution of chloroplatinic acid.

[0111] Preferably, in step (1c), a settling step is included before the calcination step. More preferably, in step (1c), a drying step is included between the settling and calcination steps. Even more preferably, the settling in step (1c) is carried out at 30°C to 50°C for 6 to 12 hours, the drying is carried out at 80°C to 120°C, and the calcination is carried out in a nitrogen atmosphere at 300°C to 500°C for 1 to 10 hours, preferably 3 to 8 hours.

[0112] In step (1d), the calcination is carried out in a hydrogen atmosphere at 350°C to 450°C for 1 hour to 10 hours, preferably 1 hour to 5 hours.

[0113] Thirdly, the present invention relates to an aromatic isomerization catalyst system, comprising:

[0114] 1) An ethylbenzene deethylation catalyst prepared according to the method of the first aspect or the second aspect, and

[0115] 2) A xylene isomerization catalyst comprising a second molecular sieve and a second binder.

[0116] Preferably, the second molecular sieve comprises a second metal, which is one or more selected from K, Rb, Cs, Sr, and Ba. More preferably, the second metal is Rb and / or Cs.

[0117] Preferably, 1% to 60%, more preferably 3% to 50%, of the cation sites of the second molecular sieve are occupied by a second metal cation.

[0118] According to the present invention, the cation sites occupied by the second metal cation in the second molecular sieve can be 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 55%, 60%, or values ​​within a range consisting of any two of the above values ​​or one of the above values ​​and one end of one of the above ranges or one end of one of the above ranges and one end of another of the above ranges.

[0119] Preferably, the total Brønsted acid content in the second molecular sieve is 50 to 200 μmol / g. More preferably, the total Brønsted acid content in the second molecular sieve is 100 to 170 μmol / g.

[0120] Preferably, the total L acid content in the second molecular sieve is 200 to 800 μmol / g. More preferably, the total L acid content in the second molecular sieve is 300 to 500 μmol / g.

[0121] According to the present invention, the amounts of Brønsted (B) and Lewis (L) acids can be measured using any method commonly used in the field of catalysts. For example, the amounts of Brønsted (B) and Lewis (L) acids can be measured using pyridine adsorption infrared spectroscopy. Alternatively, the amounts of Brønsted (B) and Lewis (L) acids can be measured using a Tensor 27 infrared spectrometer from Bruker GmbH, Germany.

[0122] Preferably, the ratio of total Brønsted acid to total Lønsted acid is 0.1:1 to 1:1, more preferably 0.1:1 to 0.6:1, and even more preferably 0.1:1 to 0.35:1.

[0123] The xylene isomerization reaction requires a weaker acidity than the ethylbenzene deethylation reaction, and increasing the number of L acid sites is beneficial for improving the selectivity of the xylene isomerization reaction. Introducing the second metal ion at the cation site can reduce the amount of Brønsted acid and increase the amount of Lewis acid, thereby achieving the aforementioned Brønsted acid to Lewis acid ratio. Under such conditions, the xylene isomerization catalyst facilitates the conversion of ortho- and m-xylenes to para-xylene while simultaneously reducing the occurrence of side reactions, thus achieving higher xylene isomerization activity and further reducing xylene loss.

[0124] Preferably, the xylene isomerization catalyst comprises 60 wt.% to 80 wt.% of a second molecular sieve and 20 wt.% to 40 wt.% of a second binder, based on the total weight of the xylene isomerization catalyst.

[0125] Preferably, the second molecular sieve is a silica-alumina molecular sieve. Preferably, the molar ratio of SiO2 to Al2O3 is 60:1 to 200:1, more preferably 80:1 to 180:1, and even more preferably 80:1 to 120:1.

[0126] According to the present invention, the average particle size of the second molecular sieve can be from 30 nm to 200 nm. Preferably, the average particle size of the second molecular sieve can be from 30 nm to 100 nm.

[0127] Preferably, the sum of the mesopore and macropore volumes of the second molecular sieve accounts for more than or equal to 55% of the total pore volume. More preferably, the sum of the mesopore and macropore volumes of the second molecular sieve accounts for 55% to 85% of the total pore volume.

[0128] According to the present invention, the second molecular sieve can be monocrystalline or polycrystalline, preferably monocrystalline. The second molecular sieve has an MFI, MEL, and / or TON topology.

[0129] Preferably, the catalyst system comprises 10 wt.% to 50 wt.% of the ethylbenzene deethylation catalyst and 50 wt.% to 90 wt.% of the xylene isomerization catalyst, based on the total weight of the catalyst system.

[0130] Preferably, the first adhesive and the second adhesive are aluminum oxide independently of each other.

[0131] In the C8 aromatic hydrocarbon isomerization process, the catalyst system according to the third aspect of the present invention can simultaneously achieve improved ethylbenzene conversion, significantly reduced xylene loss, and good xylene isomerization activity.

[0132] Fourthly, the present invention relates to a method for preparing a catalyst system according to the third aspect, comprising:

[0133] (2a) The preparation method of the ethylbenzene deethylation catalyst according to the second aspect;

[0134] (2b) The second molecular sieve and the second binder precursor are mixed, and then an inorganic acid solution is added. The mixture treated with the inorganic acid is then calcined to obtain the xylene isomerization catalyst; and

[0135] (2c) The ethylbenzene deethylation catalyst and the xylene isomerization catalyst are placed separately.

[0136] Preferably, the ethylbenzene deethylation catalyst is located in the upper layer of the catalyst bed, and the xylene isomerization catalyst is located in the lower layer of the catalyst bed.

[0137] Preferably, before step (2b), a step (2b') is included to contact the H-type molecular sieve with a salt solution of the second metal for ion exchange, i.e., the second molecular sieve is a molecular sieve obtained by ion exchange treatment with the second metal. Specifically, the H-type MFI molecular sieve can be mixed with a salt solution of the second metal for ion exchange, and then washed and dried to obtain the second molecular sieve. Preferably, the salt solution of the second metal is a chloride and / or nitrate.

[0138] Preferably, in step (2b), the weight ratio of the second molecular sieve to the second binder precursor is (60-80):(20-40).

[0139] Preferably, in step (2b), a shaping step is included before the baking step. More preferably, in step (2b), a drying step is included between the shaping and baking steps. Even more preferably, the drying is carried out at 80°C to 140°C, preferably 100°C to 120°C, and / or the baking is carried out in an air atmosphere at 500°C to 600°C.

[0140] In step (2b), the second binder precursor is partially dissolved after mixing with the inorganic acid solution, and a binder is generated after the calcination step, thereby tightly connecting the various substances through mechanical interlocking and / or chemical bonding. The second binder precursor is hydroxyl-containing and / or hydrated alumina, preferably one or more of boehmite, aluminum hydroxide, and aluminum sol, more preferably boehmite. Preferably, the inorganic acid solution is selected from one or more of dilute nitric acid, dilute sulfuric acid, and dilute hydrochloric acid.

[0141] According to the present invention, the preparation method of H-type molecular sieve may include: (i) mixing silica sol, aluminum salt solution, template agent and inorganic base uniformly, (ii) dynamically aging and dynamically crystallizing the resulting mixture, and (iii) washing, drying and calcining the crystallized product to obtain the H-type molecular sieve.

[0142] The silica sol, aluminum salt, template agent, and inorganic base have the definitions described above.

[0143] The "dynamic crystallization" can be carried out using any method and instrument commonly used in the relevant field. Preferably, the dynamic aging is carried out at a temperature of 50°C to 100°C for 6 to 48 hours, the dynamic crystallization is carried out at a temperature of 150°C to 200°C for 30 to 50 hours, the drying is carried out at a temperature of 110°C to 130°C, and / or the calcination is carried out at a temperature of 500°C to 600°C for 2 to 6 hours.

[0144] Fifthly, the present invention relates to a C8 aromatic isomerization method comprising contacting a reaction mixture comprising at least one of o-xylene and m-xylene and ethylbenzene with a catalyst system according to a third aspect or a catalyst system prepared according to a fourth aspect, wherein the reaction mixture is sequentially passed through the ethylbenzene deethylation catalyst and the xylene isomerization catalyst.

[0145] Preferably, the reaction mixture is contacted with the ethylbenzene deethylation catalyst and the xylene isomerization catalyst in the presence of hydrogen, at a temperature of 200°C to 600°C, and at a pressure of 0.5 MPa to 2 MPa, preferably 1.0 MPa to 2.0 MPa.

[0146] Preferably, the hydrogen flow rate is 20 ml / min to 50 ml / min.

[0147] Preferably, the reaction mixture comprises 0.1 wt.% to 30 wt.%, more preferably 1 wt.% to 20 wt.% of ethylbenzene, 5 wt.% to 90 wt.%, more preferably 20 wt.% to 80 wt.% of m-xylene, and 1 wt.% to 60 wt.%, more preferably 5 wt.% to 40 wt.% of o-xylene.

[0148] According to the present invention, the reaction mixture may contain a certain amount of p-xylene. For example, the reaction mixture contains 10 wt.% or less, preferably 5 wt.% or less, more preferably 1 wt.% or less of p-xylene.

[0149] According to the present invention, the reaction mixture can be fed at a rate of 5 g / h to 15 g / h. Preferably, before feeding the reaction mixture, the reactor is treated at 380°C to 450°C in the presence of hydrogen for a period of time, for example, 0.5 h to 3 h, and then the reactor temperature is set to 340°C to 400°C.

[0150] As described above, by using the aromatic isomerization catalyst system according to the present invention, improved ethylbenzene conversion, significantly reduced xylene loss, and good xylene isomerization activity can be achieved in the C8 aromatic isomerization process.

[0151] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings, but the drawings do not constitute a limitation on the present invention.

[0152] Figure 1 is a scanning electron microscope (SEM) photograph magnified 18,000 times. As can be seen from Figure 1, the first molecular sieve used in molecular sieve preparation example 1 is plate-shaped, with the a-axis and c-axis perpendicular to the b-axis, and the dimension along the b-axis is significantly smaller than the dimensions along the a-axis and c-axis, which are perpendicular to it, respectively.

[0153] As can be seen from Figure 2, since the plate-like first molecular sieve of a specific size cannot be tightly bonded to the inert material particles of a specific size in the ellipsoidal shape used as a regulator, large pores are left, thus enabling the formation of macropores between the plate-like first molecular sieve and the regulator or between parts of the plate-like first molecular sieve.

[0154] Figure 3 is a scanning electron microscope (SEM) photograph at 2200x magnification. As can be seen from Figure 3, the inert alumina used as a modifier in the embodiment has a near-ellipsoidal shape.

[0155] This application relates to the following technical solutions:

[0156] [1] An aromatic hydrocarbon isomerization catalyst, characterized in that it comprises an ethylbenzene deethylation catalyst and a xylene isomerization catalyst;

[0157] The ethylbenzene deethylation catalyst comprises a first molecular sieve, a first binder, an activity inhibitor, and a first metal;

[0158] The first molecular sieve is plate-shaped with a b-axis dimension of 0.5–5 μm and a mid-length dimension of 2–15 μm perpendicular to the b-axis, which is larger than the b-axis dimension; the active inhibitor includes Si species and C species;

[0159] The xylene isomerization catalyst includes a second molecular sieve and a second binder. The second molecular sieve includes a second metal, which is one or more selected from K, Rb, Cs, Sr, and Ba. The ratio of Brønsted acid to Lewis acid in the second molecular sieve is 0.1 to 1.0:1.

[0160] [2]. The aromatic isomerization catalyst according to item [1] is characterized in that the second metal is one or more selected from Rb, Cs, Sr, Ba, preferably Rb and / or Cs;

[0161] The proportion of the second metal, calculated as cations, in the total number of cation sites in the second molecular sieve is 1% to 60%, preferably 3% to 50%.

[0162] [3]. The aromatic isomerization catalyst according to Project [1] is characterized in that the ratio of the amount of Brønsted acid to L-acid in the second molecular sieve is 0.1 to 0.6:1, preferably 0.15 to 0.35:1.

[0163] [4]. The aromatic isomerization catalyst according to any one of items [1] to [3] is characterized in that the proportion of the second molecular sieve is 60% to 80%, and the proportion of the second binder is 20% to 40%, based on the mass of the xylene isomerization catalyst;

[0164] The second molecular sieve is a silica-alumina molecular sieve with a particle size of 50-200 nm, wherein the molar ratio of SiO2 to Al2O3 is 60-200:1, preferably 80-180:1, and more preferably 80-120:1;

[0165] The sum of the volumes of mesopores and macropores in the second molecular sieve accounts for more than or equal to 55% of the total pore volume of micropores, mesopores and macropores.

[0166] The topology of the second molecular sieve is MFI, MEL, or TON.

[0167] [5]. The aromatic isomerization catalyst according to Project [1] is characterized in that the ratio of the length dimension to the b-axis dimension in the direction perpendicular to the b-axis of the first molecular sieve is greater than or equal to 3:1, preferably greater than or equal to 5:1;

[0168] The Si species is SiO2, and the C species is the calcination product of organic ammonium.

[0169] The first metal is selected from one or more of Pt, Pd, Ru, Ir and Ni;

[0170] The first metal exists at least partially in elemental form.

[0171] [6]. The aromatic isomerization catalyst according to Project [1] is characterized in that the topological structure of the first molecular sieve is MFI, MEL, EUO or TON;

[0172] The first molecular sieve has ten-membered ring channels;

[0173] The first molecular sieve is a silica-alumina molecular sieve, wherein the molar ratio of SiO2 to Al2O3 is 30 to 130:1.

[0174] [7]. The aromatic isomerization catalyst according to Project [1] is characterized in that the proportion of the first molecular sieve is 30% to 62%, the proportion of the first binder is 22% to 64%, the proportion of the active inhibitor is 5.0% to 18%, and the proportion of the first metal is 0.01% to 0.1%, based on the total mass of the ethylbenzene deethylation catalyst;

[0175] The Si species comprise 3.0% to 17% of the total content, and the C species comprise 1.0% to 3.0% of the total content, based on the total mass of the ethylbenzene deethylation catalyst.

[0176] [8]. The aromatic isomerization catalyst according to Project [1] is characterized in that the proportion of the ethylbenzene deethylation catalyst is 10% to 50%, and the proportion of the xylene isomerization catalyst is 50% to 90%, based on the total mass of the aromatic isomerization catalyst.

[0177] [9]. A method for preparing the aromatic isomerization catalyst described in any one of items [1] to [8], characterized in that it comprises the following steps:

[0178] (1) Preparation of ethylbenzene deethylation catalyst

[0179] (S1) The first molecular sieve, the first aluminum-containing compound and the Si-containing precursor are mixed, and then an inorganic acid solution is added and mixed, then shaped and calcined to obtain intermediate product A-1.

[0180] The first molecular sieve is plate-shaped, with a b-axis dimension of 0.5–5 μm and a mid-length dimension of 2–15 μm perpendicular to the b-axis, which is larger than the b-axis dimension.

[0181] (S2) The intermediate product A-1 obtained from step (S1) is mixed with an organic ammonium solution, and then allowed to stand and calcined in an inert atmosphere to obtain intermediate product A-2.

[0182] (S3) The intermediate product A-2 obtained from step (S2) is placed in the first metal precursor solution, then allowed to stand and calcined under an inert atmosphere to obtain intermediate product A-3.

[0183] (S4) The intermediate product A-3 obtained from step (S3) is calcined in a reducing atmosphere to obtain the ethylbenzene deethylation catalyst;

[0184] (2) Preparation of xylene isomerization catalyst

[0185] (T1) The H-type molecular sieve is contacted with a salt solution of a second metal to perform ion exchange, thereby obtaining a second molecular sieve; wherein the second molecular sieve includes a second metal, which is one or more selected from K, Rb, Cs, Sr, and Ba; the ratio of Brønsted acid to Lewis acid in the second molecular sieve is 0.1 to 1.0:1.

[0186] (T2) Mix the second molecular sieve and the second aluminum-containing compound, then add an inorganic acid solution, mix, shape, and calcine to obtain the xylene isomerization catalyst;

[0187] (3) Preparation of aromatic isomerization catalyst

[0188] The ethylbenzene deethylation catalyst from step (S4) is located in the upper layer of the catalyst bed, and the xylene isomerization catalyst from step (T2) is located in the lower layer of the catalyst bed, thus obtaining the aromatic hydrocarbon isomerization catalyst.

[0189]

[0010] . The method according to item [9] is characterized in that, in step (S1), the molecular formula of the Si-containing precursor contains only one silicon atom, and the Si-containing precursor is a silane and / or a silicate ester; the silane is selected from one or more of dichlorodimethylsilane, phenyltrimethoxysilane, phenyltriethoxysilane, γ-aminopropyltriethoxysilane, and methyltriethoxysilane; the silicate ester is methyl silicate and / or ethyl silicate; and / or

[0190] The mass ratio of the first molecular sieve, the first aluminum-containing compound, and the Si-containing precursor is (1.0–10):(0.5–8.0):1.0; and / or

[0191] In step (S2), the mixing mass ratio of the intermediate product A-1 to the organic ammonium in the organic ammonium solution is (5-30):1; the organic ammonium is a quaternary ammonium base and / or a quaternary ammonium salt, the organic ammonium has a carbon number greater than or equal to 16 in its molecular formula, and the organic ammonium is one or more selected from tetrabutylammonium hydroxide, tetrabutylammonium bromide, and tetrapentylammonium hydroxide; and / or

[0192] In step (S3), the first metal precursor solution is a complex solution of the first metal.

[0193]

[0011] . The method according to item [9] is characterized in that step (S1) further includes drying between the molding and the calcination, wherein the mixing in step (S1) is carried out at 50-100°C for 2.0-24 hours, the drying is carried out at 80-120°C, and the calcination is carried out in an air atmosphere at 500-600°C for 2-6 hours; and / or

[0194] Step (S2) further includes drying between the settling and calcination, wherein the settling is performed at 20–60°C for 20–60 min, the drying is performed at 80–120°C, and the calcination is performed in a nitrogen atmosphere at 400–500°C for 4–8 h; and / or

[0195] Step (S3) further includes drying between the settling and calcination, wherein the settling is carried out at 30–50°C for 6–12 hours, the drying is carried out at 80–120°C, and the calcination is carried out in a nitrogen atmosphere at 300–500°C for 1–10 hours; and / or

[0196] The calcination described in step (S4) is carried out in a hydrogen atmosphere at 350–450°C for 1–10 hours; and / or

[0197] In step (T2), the mixing mass ratio of the second molecular sieve and the second aluminum-containing compound is (60-80):(20-40); and / or

[0198] Step (T2) also includes drying between the molding and the calcination, the drying being carried out at 80–120°C and the calcination being carried out in an air atmosphere at 500–600°C.

[0199] Example

[0200] The present invention will be further described in detail below through embodiments, but these embodiments do not limit the scope of the invention. Unless otherwise specified, the experimental instruments and raw materials involved in the following embodiments are commercially available products.

[0201] Instruments and materials:

[0202] The various embodiments were carried out using the following instruments and materials:

[0203] Silica sol: LS-30, purchased from Zhejiang Yuda Chemical Co., Ltd.

[0204] pseudoboehmite: from Sinopec Catalyst Co., Ltd.

[0205] Hydroxypropyl methylcellulose: Type I, viscosity 100 mPa·s, purchased from Bailingwei Technology Co., Ltd.

[0206] Scanning electron microscope: Hitachi S-4800 scanning electron microscope, Japan.

[0207] Nitrogen physical adsorption analyzer: Micromeritics ASAP-2010C

[0208] Thermogravimetric analyzer: Netzsch STA449 F5, Germany

[0209] Gas chromatograph: Agilent 8890, column: HP-INNOWAX

[0210] Pyridine adsorption infrared spectrometer: Tensor 27 infrared spectrometer from Bruker, Germany.

[0211] X-ray fluorescence spectrometer: Rigaku ZSX Primus IV X-ray fluorescence spectrometer, Japan, voltage 50kV, current 50mA.

[0212] Definitions of relevant parameters in the embodiment:

[0213] Median pore size: The pore size corresponding to half of the maximum pore volume during the mercury intrusion process into the catalyst pores, measured using a MicroActive AutoPore V 9600 mercury porosimeter manufactured by Micromeritics.

[0214] Average particle size: The visually estimated maximum size of 20 particles was measured using the scanning electron microscope described above, and then the arithmetic mean of the visually estimated maximum size of these 20 particles was calculated.

[0215] Moisture content: After calcining the regulator to be measured at 600℃ for 4 hours, its weight is recorded as m1, which is set as having a moisture content of 0 wt.%. The weight of the uncalcined regulator to be measured is recorded as m2. Moisture content = (m2 - m1) / m2.

[0216] The micropore volume and total pore volume were measured using the nitrogen physical adsorption instrument described above at a temperature of -196℃. The micropore volume was calculated using the t-plot method. The amount of nitrogen adsorbed at a relative pressure (p / p0) of 0.98 was the total pore volume. Subtracting the micropore volume from the total pore volume yielded the sum of the mesopore and macropore volumes.

[0217] The content of carbon-containing substances as activity inhibitors: Under air atmosphere, at a heating rate of 10℃ / min, the decrease in weight percentage between 200 and 600℃ in the thermogravimetric analysis curve is the carbon content, which is regarded as the content of carbon-containing substances.

[0218] Example 1 of molecular sieve preparation (plate-shaped molecular sieve)

[0219] 160.2 g of silica sol, 17 g of 20 wt.% aluminum sulfate solution, 29.3 g of tetrapropylammonium hydroxide, 3.5 g of sodium hydroxide, 26.9 g of sodium fluoride, and 572.8 g of deionized water were mixed thoroughly. The resulting mixture was then dynamically crystallized at 180 °C for 48 h in a molecular sieve hydrothermal crystallization reactor. The crystallized product was washed with deionized water, dried at 120 °C, and then calcined at 540 °C for 4 h to obtain sheet-like MFI molecular sieve A.

[0220] The scanning electron microscope image (magnified 18000 times) of the prepared sheet-like MFI molecular sieve A is shown in Figure 1. The SiO2 / Al2O3 molar ratio of the sheet-like MFI molecular sieve A is 60.6, the b-axis dimension of the sheet-like MFI molecular sieve A crystal is 0.75 μm, and the length of the large side surface (length in the a-axis or c-axis direction) is 5.1 μm.

[0221] Example 2 of molecular sieve preparation (plate-shaped molecular sieve)

[0222] The method was basically the same as that used in Example 1 of molecular sieve preparation, except that 19g of a 20wt.% aluminum sulfate solution was added to obtain plate-like MFI molecular sieve B. The prepared plate-like MFI molecular sieve B had a SiO2 / Al2O3 molar ratio of 51.9, a b-axis dimension of 0.52μm, and a large lateral length (length along the a-axis or c-axis) of 3.8μm.

[0223] Example 3 of molecular sieve preparation (plate-shaped molecular sieve)

[0224] The method is basically the same as that used in Example 1 for preparing molecular sieves, except that 14g of a 20wt.% aluminum sulfate solution was added to obtain plate-like MFI molecular sieve C. The prepared plate-like MFI molecular sieve C has a SiO2 / Al2O3 molar ratio of 81.3, a b-axis dimension of 0.88μm, and a large lateral length (length along the a-axis or c-axis) of 7.2μm.

[0225] Example 4 of molecular sieve preparation (non-plate molecular sieve)

[0226] 400g of silica sol, 42.8g of 20wt.% aluminum sulfate solution, 48.9g of tetrapropylammonium hydroxide, and 6.6g of sodium hydroxide were mixed thoroughly. The resulting mixture was dynamically aged at 80℃ for 24h and dynamically crystallized at 180℃ for 48h in a molecular sieve hydrothermal crystallization reactor. The crystallized product was washed with deionized water, dried at 120℃, and then calcined at 540℃ for 4h to obtain non-sheet MFI molecular sieve D.

[0227] The prepared non-sheet MFI molecular sieve D has a SiO2 / Al2O3 molar ratio of 67.4, an average particle size of 50 nm, and a spherical shape.

[0228] Example of preparation of inert alumina

[0229] 100g of pseudoboehmite (alumina content 75wt.%) was placed in a muffle furnace and heated from room temperature to 400℃ at a heating rate of 5℃ / min. The temperature was then maintained at 400℃ for 4 hours. After cooling to room temperature, inert alumina was obtained.

[0230] The scanning electron microscope image (2200x magnification) of the prepared inert alumina is shown in Figure 3. It is ellipsoidal in shape, with an average particle size of 39 μm and a water content of 3.5 wt%.

[0231] Example 1 (Ethylbenzene Deethylation Catalyst)

[0232] 53 g of sheet-like MFI molecular sieve A prepared in Molecular Sieves Preparation Example 1, 38.9 g of boehmite (alumina content 75 wt.%), 28 g of phenyltriethoxysilane, and 10.1 g of inert alumina prepared in the above-mentioned inert alumina preparation example were mixed at 80 °C for 12 hours. A 5 wt.% dilute nitric acid solution was added to the mixture, and after mixing them evenly, they were extruded into shape. The shaped body was dried at 120 °C and then calcined at 540 °C for 4 hours in an air atmosphere to obtain intermediate product A-1.

[0233] Take 99g of intermediate product A-1 and mix it with 200g of a 5.0wt.% tetrapentylammonium hydroxide solution. Let the mixture stand at 50℃ for 30min, dry it at 120℃, and calcine it at 420℃ for 6 hours in a nitrogen atmosphere to obtain intermediate product A-2.

[0234] Intermediate product A-2 was added to 139 mL of chloroplatinic acid aqueous solution (Pt element content 0.216 g / L). The mixture was allowed to stand at 35 °C for 8 hours. The intermediate product A-2 treated with chloroplatinic acid aqueous solution was taken out and dried at 100 °C. It was then calcined at 420 °C for 6 hours under a nitrogen atmosphere to obtain intermediate product A-3.

[0235] Intermediate product A-3 was treated in a hydrogen atmosphere at 420°C for 2 hours to obtain catalyst E1. The median pore size, measured by mercury porosimetry, was 617 nm. The weight percentages of the components were as follows: 52.4 wt.% of plate-like MFI molecular sieve, 28.8 wt.% of binder (based on Al2O3), 9.9 wt.% of inert alumina, 6.9 wt.% of Si-containing substances (based on SiO2) and 2 wt.% of C-containing substances (based on SiO2) as activity inhibitors, and 0.03 wt.% of platinum.

[0236] Example 2 (Ethylbenzene Deethylation Catalyst)

[0237] The preparation method is basically the same as that in Example 1, except that 53g of the sheet-like MFI molecular sieve B prepared in Example 2 was added to obtain catalyst E2. The median pore size measured by mercury porosimeter was 506nm. The weight percentages of each component are as follows: sheet-like MFI molecular sieve 52wt.%, binder based on Al2O3 28.6wt.%, inert alumina 9.8wt.%, Si-containing substances based on SiO2 6.9wt.% and C-containing substances based on SiO2 2.6wt.% as activity inhibitors, and platinum 0.03wt.%.

[0238] Example 3 (Ethylbenzene Deethylation Catalyst)

[0239] The preparation method is basically the same as that in Example 1, except that 53g of the sheet-like MFI molecular sieve C prepared by molecular sieve preparation Example 3 is added to obtain catalyst E3. The median pore size measured by mercury porosimeter is 698nm. The weight percentage of each component is as follows: sheet-like MFI molecular sieve 52.5wt.%, binder based on Al2O3 28.9wt.%, inert alumina 9.9wt.%, Si-containing substances based on SiO2 6.9wt.% and C-containing substances based on SiO2 1.8wt.% as activity inhibitors, and platinum 0.03wt.%.

[0240] Comparative Example 1 (Ethylbenzene Deethylation Catalyst)

[0241] The preparation method is basically the same as that in Example 1, except that the inert alumina regulator was not added, resulting in catalyst C1 with a median pore size of 97 nm.

[0242] Comparative Example 2 (Ethylbenzene Deethylation Catalyst)

[0243] The preparation method is basically the same as that in Example 1, except that the added molecular sieve is a non-sheet-like MFI molecular sieve D prepared by molecular sieve preparation 4, resulting in catalyst C2 with a median pore size of 35 nm.

[0244] Comparative Example 3 (Ethylbenzene Deethylation Catalyst)

[0245] The preparation method is basically the same as that in Example 1, except that inert alumina is replaced with hydroxypropyl methylcellulose to obtain catalyst C3 with a median pore size of 135 nm.

[0246] Test Example 1

[0247] The performance of catalysts E1-E3 and C1-C3 was evaluated using a microreactor (fixed-bed microreactor evaluation device). 1 g of catalysts E1-E3 and C1-C3 were loaded into their respective microreactor evaluation devices. Hydrogen gas was introduced at a flow rate of 35.2 mL / min, and the pressure inside the reactor was 1.6 MPa. The reactor was treated at 400 °C for 1 hour, and then the temperature was lowered to 380 °C. A feedstock, namely a C8 aromatic reaction mixture containing 5.42 wt.% ethylbenzene, 0.14 wt.% p-xylene, 63.61 wt.% m-xylene, 29.23 wt.% o-xylene, and the balance non-aromatic components, was added to the microreactor at a rate of 25 g / h. Samples were taken after 4 hours of reaction. The sample composition was analyzed using gas chromatography (heating from 70 °C to 120 °C at a rate of 5 °C / min, then to 170 °C at a rate of 25 °C / min and held for 8 min).

[0248] The ethylbenzene conversion rate C is calculated using the following formula. EB And the xylene loss s, the calculation results are shown in Table 1:

[0249] Ethylbenzene conversion rate C EB = (5.42% - m) EB ) / 5.42%×100%

[0250] xylene loss s=1-(m PX +m MX +m OX ) / (0.14% + 63.61% + 29.23%)

[0251] Where m EB m PX mMX m OX The values ​​represent the weight percentages of ethylbenzene, p-xylene, m-xylene, and o-xylene in the reaction products, respectively.

[0252] Table 1

[0253] As can be seen from the data in Table 1, compared with Comparative Examples 1-3, the ethylbenzene deethylation catalyst of Example 1 of the present invention can achieve improved ethylbenzene conversion and significantly reduced xylene loss. The ethylbenzene deethylation catalysts of Examples 2-3 of the present invention also provide good ethylbenzene conversion and significantly reduced xylene loss.

[0254] Example 4 (Aromatic Hydrocarbon Isomerization Catalyst System S1)

[0255] The preparation method of the ethylbenzene deethylation catalyst is the same as that in Example 1, yielding catalyst E1.

[0256] Preparation of hydrogen-form MFI molecular sieve: 400g of silica sol, 29.4g of 20wt.% aluminum sulfate solution, 97.5g of tetrapropylammonium hydroxide, and 11.2g of sodium hydroxide were mixed thoroughly. The resulting mixture was dynamically aged at 80℃ for 24h and dynamically crystallized at 180℃ for 48h in a molecular sieve hydrothermal crystallization reactor. The crystallized product was washed with deionized water, dried at 120℃, and then calcined at 540℃ for 4h to obtain MFI molecular sieve F1, which has a spherical shape.

[0257] 200g of MFI molecular sieve F1 was mixed with 1000mL of 0.8mol / L NH4Cl solution and stirred at 80℃ for 1h for ammonium exchange to obtain intermediate B-1. The ammonium exchange operation was repeated on intermediate B-1 to obtain intermediate B-2 after two ammonium exchange cycles. Intermediate B-2 after two ammonium exchange cycles was filtered out and then mixed with 1000mL of deionized water and washed by stirring at 80℃ for 1h. The washing step was repeated for a second wash. Intermediate B-2 after two washes was dried at 120℃ and calcined at 500℃ for 4h to obtain hydrogen-form MFI molecular sieve F2 (particle size 50nm, SiO2 to Al2O3 molar ratio 89.6, micropore volume 0.15cm³). 3 / g, the sum of the volumes of mesopores and macropores is 0.22cm. 3 / g).

[0258] Preparation of xylene isomerization catalyst: 100g of hydrogen-form MFI molecular sieve F2 was mixed with 500mL of 0.04mol / L RbCl solution and stirred at 80℃ for 1h for ion exchange. The ion-exchanged MFI molecular sieve was washed with deionized water and then dried at 120℃ to obtain Rb-containing MFI molecular sieve F.

[0259] Pyridine adsorption infrared spectroscopy analysis revealed that the prepared Rb-containing MFI molecular sieve F contained 148 μmol / g of Brønsted acid and 339 μmol / g of Lewis acid, with a Brønsted acid to Lewis acid ratio of 0.44:1. X-ray fluorescence spectroscopy analysis showed that Rb ions accounted for 33.0% of the total number of cation sites in MFI molecular sieve F.

[0260] 70g of Rb-containing MFI molecular sieve F and 40g of pseudoboehmite (75wt.% alumina) were mixed evenly. A 5wt.% dilute nitric acid solution was added to the mixture, and after mixing evenly, the mixture was extruded into shape. The shaped body was dried at 120°C and calcined in air at 550°C for 4 hours to obtain catalyst X1.

[0261] By placing 0.15g of catalyst E1 in the upper layer of the catalyst bed and 0.85g of catalyst X1 in the lower layer of the catalyst bed, a 1g catalyst system S1 is obtained.

[0262] Example 5 (Aromatic Hydrocarbon Isomerization Catalyst System S2)

[0263] Catalyst S2 was prepared in basically the same manner as in Example 4, except that catalyst S2 contained 0.25 g of catalyst E1 and 0.75 g of catalyst X1.

[0264] Example 6 (Aromatic Hydrocarbon Isomerization Catalyst System S3)

[0265] Preparation of the ethylbenzene deethylation catalyst: 60g of sheet-like MFI molecular sieve A prepared by molecular sieve preparation example 1, 32g of pseudoboehmite (alumina content 75 wt.%), 36g of phenyltriethoxysilane, and 6.1g of inert alumina prepared by the inert alumina preparation example were mixed at 80°C for 12 hours. A 5 wt.% dilute nitric acid solution was added to the mixture, and after mixing them evenly, they were extruded into shape. The shaped body was dried at 120°C and then calcined at 540°C for 4 hours in air atmosphere to obtain intermediate product A-1'.

[0266] Take 99g of intermediate product A-1' and mix it with 200g of tetrapentylammonium hydroxide solution with a concentration of 2.5wt.%. Let the mixture stand at 50℃ for 30min, dry it at 120℃, and calcine it at 420℃ for 6 hours in a nitrogen atmosphere to obtain intermediate product A-2'.

[0267] Intermediate product A-2' was added to 139 mL of chloroplatinic acid solution (Pt content 0.216 g / L). The mixture was allowed to stand at 35 °C for 8 hours. The intermediate product A-2' treated with chloroplatinic acid aqueous solution was taken out and dried at 100 °C. It was then calcined at 420 °C for 6 hours under a nitrogen atmosphere to obtain intermediate product A-3'.

[0268] Intermediate product A-3' was treated in a hydrogen atmosphere at 420°C for 2 hours to obtain catalyst E4. The median pore size measured by mercury porosimetry was 421 nm. The weight percentages of each component were as follows: 60 wt.% of plate-like MFI molecular sieve, 24 wt.% of binder (based on Al2O3), 9 wt.% of inert alumina, 6 wt.% of Si-containing substances (based on SiO2) and 1 wt.% of C-containing substances (based on SiO2) as activity inhibitors, and 0.03 wt.% of platinum.

[0269] The preparation method of the xylene isomerization catalyst is the same as in Example 4, and catalyst X1 is obtained.

[0270] 0.15g of catalyst E4 is placed in the upper layer of the catalyst bed, and 0.85g of catalyst X1 is placed in the lower layer of the catalyst bed to obtain catalyst system S3.

[0271] Example 7 (Aromatic Hydrocarbon Isomerization Catalyst System S4)

[0272] The preparation method of the ethylbenzene deethylation catalyst is the same as in Example 6, yielding catalyst E4.

[0273] The preparation method of hydrogen-form MFI molecular sieve is the same as in Example 4, and hydrogen-form MFI molecular sieve F2 is obtained.

[0274] Preparation of xylene isomerization catalyst: 100g of hydrogen-form MFI molecular sieve F2 was mixed with 900mL of 0.04mol / L CsCl solution and stirred at 80℃ for 1h for ion exchange. The ion-exchanged MFI molecular sieve was washed with deionized water and then dried at 120℃ to obtain Cs-containing MFI molecular sieve G.

[0275] Pyridine adsorption infrared spectroscopy revealed that the prepared Cs-containing MFI molecular sieve G contained 126 μmol / g of Brønsted acid and 432 μmol / g of Lewis acid, with a Brønsted acid to Lewis acid ratio of 0.29:1. X-ray fluorescence spectroscopy (XRF) analysis showed that Cs ions accounted for 9.4% of the total number of cation sites in the MFI molecular sieve G.

[0276] 70g of Cs-containing MFI molecular sieve G and 40g of pseudoboehmite (75wt.% alumina) were mixed evenly. A 5wt.% dilute nitric acid solution was added to the mixture, and after mixing evenly, the mixture was extruded into shape. The shaped body was dried at 120°C and calcined in air at 550°C for 4 hours to obtain catalyst X2.

[0277] By placing 0.25g of catalyst E4 in the upper layer of the catalyst bed and 0.75g of catalyst X2 in the lower layer of the catalyst bed, 1g of catalyst system S4 is obtained.

[0278] Example 8 (Aromatic Hydrocarbon Isomerization Catalyst System S5)

[0279] Catalyst system S5 was prepared in accordance with the method of Example 7, except that catalyst system S5 contained 0.45g of catalyst E4 and 0.55g of catalyst X2.

[0280] Comparative Example 4 (Aromatic Hydrocarbon Isomerization Catalyst System R1)

[0281] The catalyst system R1 is basically the same as S1, except that 0.15g of catalyst E1 is replaced with 0.15g of catalyst C1.

[0282] Comparative Example 5 (Aromatic Hydrocarbon Isomerization Catalyst System R2)

[0283] The catalyst system R2 is basically the same as S1, except that 0.15g of catalyst E1 is replaced with 0.15g of catalyst C2.

[0284] Comparative Example 6 (Aromatic Hydrocarbon Isomerization Catalyst System R3)

[0285] The catalyst system R3 is basically the same as S1, except that 0.15g of catalyst E1 is replaced with 0.15g of catalyst C3.

[0286] Test Example 2

[0287] The performance of aromatic isomerization catalyst systems S1-S5 and R1-R3 was evaluated using a microreactor (fixed-bed microreactor evaluation device). Catalyst systems S1-S5 and R1-R3 were respectively loaded into their respective microreactor evaluation devices, with hydrogen flow rate at 35.2 mL / min and reactor pressure at 1.6 MPa. The reactors were treated at 400 °C for 1 hour, then the temperature was lowered to 380 °C. The feedstock, a C8 aromatic reaction mixture comprising 5.42 wt.% ethylbenzene, 0.14 wt.% p-xylene, 63.61 wt.% m-xylene, 29.23 wt.% o-xylene, and the balance non-aromatic components, was added to the microreactor at a rate of 10 g / h. Samples were taken after 4 hours of reaction. The sample composition was analyzed using gas chromatography (heating from 70 °C to 120 °C at a rate of 5 °C / min, then to 170 °C at a rate of 25 °C / min and held for 8 min).

[0288] The ethylbenzene conversion rate C is calculated using the following formula. EB The percentage of p-xylene (PX / X) in the product xylene and the xylene loss (s) are calculated and the results are shown in Table 2.

[0289] Ethylbenzene conversion rate C EB = (5.42% - m) EB ) / 5.42%×100%

[0290] The proportion of p-xylene in the product xylene is PX / X=m PX / (m PX +m MX +m OX )×100%

[0291] xylene loss s=1-(m PX +m MX +m OX ) / (0.14% + 63.61% + 29.23%)

[0292] Where m EB m PX m MX m OX The values ​​represent the weight percentages of ethylbenzene, p-xylene, m-xylene, and o-xylene in the reaction products, respectively.

[0293] Table 2

[0294] As can be seen from the data in Table 2, compared with Comparative Examples 4-6, the aromatic isomerization catalyst system of Example 4 of the present invention can achieve improved ethylbenzene conversion, comparable xylene isomerization activity, and significantly reduced xylene loss. The aromatic isomerization catalyst systems of Examples 5-8 of the present invention also achieve improved ethylbenzene conversion, comparable xylene isomerization activity, and significantly reduced xylene loss.

[0295] The present application has been described above with reference to preferred embodiments; however, these embodiments are merely exemplary and illustrative. Various substitutions and modifications can be made to the present application based on these embodiments, all of which fall within the protection scope of the present application.

Claims

1. An ethylbenzene deethylation catalyst comprising a first molecular sieve, a first binder, a modifier, an activity inhibitor, and a first metal, and having a volume median pore diameter of 300-1000 nm, preferably 350-800 nm, more preferably 400-700 nm; the first molecular sieve is plate-like, and the b-axis direction size of the first molecular sieve crystal is 0.5-5 μm, preferably 0.5-3 μm, more preferably 0.5-1 μm, at least one of the a-axis direction and the c-axis direction has a size larger than the b-axis direction and is 2-15 μm, preferably 2-10 μm, more preferably 3-8 μm, the modifier is an inert substance, preferably an inert oxide, having an average particle diameter of 5-100 μm, preferably 10-80 μm, more preferably 20-60 μm, still more preferably 30-50 μm, and the activity inhibitor comprises a Si-containing substance and a C-containing substance.

2. The catalyst according to claim 1, wherein the a-axis and the c-axis of the first molecular sieve crystal are perpendicular to the b-axis, respectively, and the ratio of the longer one of the a-axis direction size and the b-axis direction size to the b-axis direction size is greater than or equal to 3:1, preferably 5:1 to 50:1, more preferably 5:1 to 10:

1.

3. The catalyst according to claim 1 or 2, wherein the modifier is one or more selected from the group consisting of inert alumina, inert silica, inert titania, and inert magnesia, preferably selected from the group consisting of inert alumina and / or inert silica; and / or the inert substance is a regular sphere, a spheroid, an ellipsoid, and / or a quasi-ellipsoid; and / or the first molecular sieve is a silicoalumina molecular sieve; and / or the first binder is alumina and / or silica, preferably alumina.

4. The catalyst according to any one of the preceding claims, wherein the ethylbenzene deethylation catalyst comprises 30 wt.% to 80 wt.%, preferably 45 wt.% to 70 wt.% of the first molecular sieve, 20 wt.% to 60 wt.%, preferably 20 wt.% to 40 wt.% of the first binder, 1 wt.% to 15 wt.%, preferably 5 wt.% to 15 wt.% of the modifier, 1 wt.% to 18 wt.%, preferably 5 wt.% to 15 wt.% of the activity inhibitor, and 0.01 wt.% to 0.1 wt.%, preferably 0.01 wt.% to 0.05 wt.% of the first metal, based on the total weight of the ethylbenzene deethylation catalyst, and / or the ethylbenzene deethylation catalyst comprises 3.0 wt.% to 17 wt.%, preferably 3.0 wt.% to 10 wt.% of the Si-containing substance and 0.5 wt.% to 5.0 wt.%, preferably 1.0 wt.% to 3.0 wt.% of the C-containing substance, based on the total weight of the ethylbenzene deethylation catalyst.

5. The catalyst according to any one of the preceding claims, wherein the first metal is one or more selected from the group consisting of Pt, Pd, Ru, Ir, and Ni; and / or the first metal is at least partially or substantially entirely present in the form of a zero-valent element; and / or the first molecular sieve has a ten-membered ring channel; and / or the first molecular sieve has a ten-membered ring channel; and / or The first molecular sieve is a silicoalumina molecular sieve having a molar ratio of SiO2to Al2O3of 30:1 to 130:1, preferably 40:1 to 90:1, more preferably 45:1 to 65:

1.

6. A method for preparing the catalyst according to any one of claims 1 to 5, comprising: (1a) mixing a first molecular sieve, a first binder precursor, a modifier, and a Si-containing substance precursor as an activity inhibitor, adding a solution of inorganic acid, and then calcining the inorganic acid-treated mixture to obtain an intermediate product A-1; (1b) mixing the intermediate product A-1 with an organic ammonium solution, and then calcining the mixture in an inert atmosphere to obtain an intermediate product A-2; (1c) impregnating the intermediate product A-2 in a first metal precursor solution, then taking out the first metal precursor-treated intermediate product A-2 and calcining it in an inert atmosphere to obtain an intermediate product A-3; and (1d) calcining the intermediate product A-3 in a reducing atmosphere to obtain the ethylbenzene deethylation catalyst.

7. The method according to claim 6, wherein the water content of the modifier in step (1a) is 0% to 5%.

8. The method according to claim 6 or 7, wherein in step (1a), the Si-containing substance precursor molecule has one silicon atom and the Si-containing substance precursor is selected from the group consisting of silanes and / or silicates; preferably, the silanes are one or more selected from the group consisting of dichlorodimethylsilane, phenyltrimethoxysilane, phenyltriethoxysilane, γ-aminopropyltriethoxysilane, methyltriethoxysilane; preferably, the silicates are methyl silicate and / or ethyl silicate; and / or in step (1a), the weight ratio of the first molecular sieve, the first binder precursor, the Si-containing substance precursor, and the modifier is (1.0-10):(0.5-8.0):1.0:(0.1-1.0); and / or in step (1a), the binder precursor is a hydroxyl-containing and / or water-containing alumina, preferably one or more selected from the group consisting of pseudoboehmite, aluminum hydroxide, and aluminum sol, more preferably pseudoboehmite; and / or in step (1b), the weight ratio of the intermediate product A-1 to the organic ammonium in the organic ammonium solution is (5-30):1; and the organic ammonium is a quaternary ammonium base and / or a quaternary ammonium salt and has greater than or equal to 16 carbon atoms, preferably the organic ammonium is one or more selected from the group consisting of tetrabutylammonium hydroxide, tetrabutylammonium bromide, tetrapentylammonium hydroxide; and / or in step (1c), the first metal precursor solution is an aqueous complex of the first metal, preferably an aqueous solution of chloroplatinic acid.

9. An aromatic isomerization catalyst system comprising 1) an ethylbenzene deethylation catalyst according to any one of claims 1 to 5 or prepared according to the method of any one of claims 6 to 8, and 2) a xylene isomerization catalyst comprising a second molecular sieve and a second binder.

10. The catalyst system according to claim 9, wherein the second molecular sieve comprises a second metal, the second metal being one or more selected from K, Rb, Cs, Sr, and Ba. Preferably, 1% to 60%, more preferably 3% to 50%, of the cation sites in the second molecular sieve are occupied by a second metal cation; and / or The second molecular sieve has a total Brønsted acid content of 50 to 200 μmol / g, preferably 100 to 170 μmol / g, a total Lewis acid content of 200 to 800 μmol / g, preferably 300 to 500 μmol / g, and a total Brønsted acid content / total Lewis acid content ratio of 0.1:1 to 1:1, preferably 0.1:1 to 0.6:1, more preferably 0.1:1 to 0.35:

1.

11. The catalyst system according to claim 9 or 10, wherein the xylene isomerization catalyst comprises 60 wt.% to 80 wt.% of a second molecular sieve and 20 wt.% to 40 wt.% of a second binder, based on the total weight of the xylene isomerization catalyst; and / or The second molecular sieve is a silica-alumina molecular sieve with an average particle size of 30 nm to 200 nm, preferably 30 nm to 100 nm, wherein the molar ratio of SiO2 to Al2O3 is 60:1 to 200:1, preferably 80:1 to 180:1, more preferably 80:1 to 120:1; and / or The sum of the mesopore and macropore volumes of the second molecular sieve accounts for more than or equal to 55% of the total pore volume, preferably 55% to 85%.

12. The catalyst system according to any one of claims 9 to 11, wherein the catalyst system comprises 10 wt.% to 50 wt.% of the ethylbenzene deethylation catalyst and 50 wt.% to 90 wt.% of the xylene isomerization catalyst, based on the total weight of the catalyst system; and / or The first adhesive and the second adhesive are aluminum oxide, which are independent of each other.

13. A method for preparing the catalyst system according to any one of claims 9 to 12, comprising: (2a) The method for preparing the ethylbenzene deethylation catalyst according to any one of claims 6 to 8; (2b) Mix the second molecular sieve and the second binder precursor, then add an inorganic acid solution, and then calcine the mixture treated with the inorganic acid to obtain the xylene isomerization catalyst; and (2c) The ethylbenzene deethylation catalyst and the xylene isomerization catalyst are placed separately. Preferably, the ethylbenzene deethylation catalyst is placed in the upper layer of the catalyst bed and the xylene isomerization catalyst is placed in the lower layer of the catalyst bed.

14. The method according to claim 13, wherein before step (2b), it further comprises step (2b') contacting the H-type molecular sieve with a salt solution of the second metal to perform ion exchange, thereby obtaining the second molecular sieve.

15. A C8 aromatics isomerization process comprising contacting a reaction mixture comprising at least one of o-xylene and m-xylene and ethylbenzene with a catalyst system according to any one of claims 9 to 12 or a catalyst system prepared according to the process of claim 13 or 14, wherein the reaction mixture is passed sequentially through an ethylbenzene de-ethylation catalyst and a xylene isomerization catalyst; Preferably, the reaction mixture is contacted with the ethylbenzene de-ethylation catalyst and the xylene isomerization catalyst separately in the presence of hydrogen at a temperature of 200 to 600 °C and at a pressure of 0.5 to 2.0 MPa, preferably 1.0 to 2.0 MPa; and / or Preferably, the reaction mixture comprises 0.1 to 30 wt.%, preferably 1 to 20 wt.% of ethylbenzene, 5 to 90 wt.%, preferably 20 to 80 wt.% of m-xylene and 1 to 60 wt.%, preferably 5 to 40 wt.% of o-xylene.

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