Hydrogen-type boron-containing EU-1 molecular sieve and preparation method thereof, C8 aromatic hydrocarbon isomerization catalyst and preparation method and application thereof

Abstract

The present invention relates to the field of catalyst technology, and discloses a hydrogen-type boron-containing EU-1 molecular sieve and a preparation method thereof, a C8 aromatic hydrocarbon isomerization catalyst and a preparation method and application thereof. The molecular sieve contains metal cations, and the metal cations are alkali metal cations with an atomic number ≮19 and / or alkaline earth metal cations with an atomic number ≮19; in the hydrogen-type boron-containing EU-1 molecular sieve, the ratio of the molar amount of the metal cations, the molar amount of silicon atoms, and the sum of the molar amounts of boron atoms and aluminum atoms is 0.05-0.7:10-100:1, and the molar ratio of the boron atoms to the aluminum atoms is 0.1-1.5:1. The C8 aromatic hydrocarbon isomerization catalyst provided by the present invention is used for catalyzing the isomerization reaction of C8 aromatic hydrocarbons, and can improve the yield of C8 aromatic hydrocarbons while maintaining a high isomerization activity.

Description

Technical Field

[0001] The present invention relates to the field of catalyst technology, and in particular to a hydrogen-type boron-containing EU-1 molecular sieve and a preparation method thereof, a C8 aromatic hydrocarbon isomerization catalyst and a preparation method and application thereof. Background Art

[0002] C8 aromatics are important basic chemical raw materials. Their main components are ethylbenzene (EB), meta-xylene (MX), para-xylene (PX), and o-xylene (OX). They are widely used in the production of synthetic fibers, synthetic resins, medicines, pesticides, etc., among which PX is the most widely used.

[0003] At present, the main way to produce PX industrially is to separate high-purity PX products from mixed C8 aromatics through an adsorption separation device. The remaining PX-depleted material undergoes a xylene isomerization reaction to regenerate a product with a PX composition close to thermodynamic equilibrium, and then returns to the adsorption separation device to separate the PX.

[0004] With the rapid growth of my country's economy, the demand for PX is also increasing. Therefore, increasing PX production through xylene isomerization technology has become an important means of PX production.

[0005] Catalyst performance is crucial in the xylene isomerization reaction. Depending on the ethylbenzene conversion pathway, xylene isomerization catalysts can be divided into two types: ethylbenzene conversion catalysts, whose primary active components are MOR and EUO molecular sieves, can isomerize ethylbenzene to xylenes, but the ethylbenzene conversion rate is typically low; and ethylbenzene deethylation catalysts, whose primary active component is ZSM-5 molecular sieve, deethylate ethylbenzene to benzene. Ethylbenzene deethylation catalysts are gaining increasing attention due to their high ethylbenzene conversion rate, reduced plant energy consumption, and the absence of benzene as a byproduct.

[0006] During the aforementioned catalytic reaction, the xylene isomerization reaction between MX and OX also occurs, accompanied by side reactions such as xylene disproportionation, xylene transalkylation, and hydrocracking, resulting in a decrease in xylene yield. Therefore, maintaining high xylene isomerization activity and high xylene yield has long been a research hotspot in the field of xylene isomerization catalysts.

[0007] CN108996517A discloses a multi-level pore and wide silicon-aluminum ratio EU-1 molecular sieve and its preparation method, which is used in the xylene isomerization reaction and has good xylene isomerization activity and selectivity, but has high xylene loss.

[0008] Therefore, it is of great significance to develop a C8 aromatics isomerization catalyst with low xylene loss and good isomerization activity and selectivity. Summary of the Invention

[0009] The purpose of the present invention is to overcome the problem that the existing C8 aromatic hydrocarbon isomerization catalyst cannot take into account both isomerization activity and C8 aromatic hydrocarbon yield.

[0010] In order to achieve the above-mentioned purpose, the first aspect of the present invention provides a hydrogen-type boron-containing EU-1 molecular sieve, which contains metal cations, and the metal cations are alkali metal cations with atomic number ≮19 and / or alkaline earth metal cations with atomic number ≮19; in the hydrogen-type boron-containing EU-1 molecular sieve, the ratio of the molar amount of the metal cations, the molar amount of silicon atoms and the sum of the molar amounts of boron atoms and aluminum atoms is 0.05-0.7:10-100:1, and the molar ratio of the boron atoms to the aluminum atoms is 0.1-1.5:1.

[0011] The second aspect of the present invention provides a method for preparing the hydrogen-type boron-containing EU-1 molecular sieve described in the first aspect, the method comprising:

[0012] (1) first mixing a silicon source, an aluminum source, a boron source, an alkali metal hydroxide, water, and a template agent to obtain a molecular sieve synthesis gel;

[0013] (2) crystallizing the molecular sieve synthesis gel to obtain a crystallized product, and sequentially performing a first drying and a first calcination on the crystallized product to obtain a first solid material;

[0014] (3) sequentially subjecting the first solid material to a first reaction with an ammonium salt solution, and sequentially subjecting the product obtained after the first reaction to a second drying and a second roasting to obtain a second solid material;

[0015] (4) performing a second reaction on the second solid material and the metal salt solution in sequence, and performing a third drying on the product obtained after the second reaction.

[0016] The third aspect of the present invention provides a C8 aromatic hydrocarbon isomerization catalyst, which includes a composite carrier and metallic platinum loaded on the composite carrier, and the content of the metallic platinum is 0.05-1.0 mass% based on the total dry mass of the composite carrier; the composite carrier includes aluminum oxide and the hydrogen-type boron-containing EU-1 molecular sieve described in the first aspect, and the content of the aluminum oxide is 10-90 mass% and the content of the hydrogen-type boron-containing EU-1 molecular sieve is 10-90 mass% based on the total dry mass of the composite carrier.

[0017] A fourth aspect of the present invention provides a method for preparing a C8 aromatics isomerization catalyst, the method comprising the following steps:

[0018] (I) mixing the hydrogen-type boron-containing EU-1 molecular sieve described in the first aspect with alumina (I), and sequentially extruding, drying, and calcining the product obtained after the mixing (I) to obtain a composite support;

[0019] (II) mixing the composite support with a platinum compound solution for impregnation, and sequentially drying and calcining the impregnated solid material.

[0020] The amount of the hydrogenated boron-containing EU-1 molecular sieve and / or the alumina is controlled so that the content of the alumina in the composite support is 10-90% by mass and the content of the hydrogenated boron-containing EU-1 molecular sieve is 10-90% by mass on a dry basis.

[0021] The metal cation is an alkali metal cation with an atomic number ≮19 and / or an alkaline earth metal cation with an atomic number ≮19;

[0022] The amount of the platinum compound solution is controlled so that the content of metallic platinum in the catalyst based on the composite support on a dry basis is 0.05-1.0% by mass.

[0023] The fifth aspect of the present invention provides a C8 aromatic hydrocarbon isomerization catalyst prepared by the method described in the fourth aspect.

[0024] The sixth aspect of the present invention provides the use of the C8 aromatic hydrocarbon isomerization catalyst described in the third aspect or the fifth aspect in catalyzing the C8 aromatic hydrocarbon isomerization reaction.

[0025] The C8 aromatic hydrocarbon isomerization catalyst provided by the present invention is used to catalyze the isomerization reaction of C8 aromatic hydrocarbons, and can improve the yield of C8 aromatic hydrocarbons while maintaining a high isomerization activity. DETAILED DESCRIPTION

[0026] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0027] In the present invention, unless otherwise specified, the room temperature or normal temperature refers to 25±2°C.

[0028] In the present invention, unless otherwise stated, the pressures mentioned are gauge pressures.

[0029] As described above, the first aspect of the present invention provides a hydrogen-type boron-containing EU-1 molecular sieve, which contains metal cations, and the metal cations are alkali metal cations with atomic number ≮19 and / or alkaline earth metal cations with atomic number ≮19; in the hydrogen-type boron-containing EU-1 molecular sieve, the ratio of the molar amount of the metal cations, the molar amount of silicon atoms and the sum of the molar amounts of boron atoms and aluminum atoms is 0.05-0.7:10-100:1, and the molar ratio of the boron atoms to the aluminum atoms is 0.1-1.5:1.

[0030] Preferably, the metal cation is selected from K + , Rb + 、Cs + , Ca 2+ 、Sr 2+ 、Ba 2+ At least one of .

[0031] According to a particularly preferred embodiment, the metal cation is selected from K + 、Cs + , Ca 2+ The inventors have found that in this preferred embodiment, a boron-containing EU-1 molecular sieve with higher isomerization activity can be obtained.

[0032] Preferably, in the hydrogenated boron-containing EU-1 molecular sieve, the ratio of the molar amount of the metal cations, the molar amount of the silicon atoms, and the sum of the molar amounts of the boron atoms and the aluminum atoms is 0.05-0.5:10-60:1. The inventors have discovered that, using this preferred embodiment, the hydrogenated boron-containing EU-1 molecular sieve obtained can achieve higher isomerization activity and C8 aromatic hydrocarbon yield in the isomerization reaction of C8 aromatic hydrocarbons.

[0033] Preferably, in the hydrogen-type boron-containing EU-1 molecular sieve, the molar ratio of the boron atoms to the aluminum atoms is 0.1-1:1.

[0034] As mentioned above, the second aspect of the present invention provides a method for preparing the hydrogen-type boron-containing EU-1 molecular sieve described in the first aspect, the method comprising:

[0035] (1) first mixing a silicon source, an aluminum source, a boron source, an alkali metal hydroxide, water, and a template agent to obtain a molecular sieve synthesis gel;

[0036] (2) crystallizing the molecular sieve synthesis gel to obtain a crystallized product, and sequentially performing a first drying and a first calcination on the crystallized product to obtain a first solid material;

[0037] (3) sequentially subjecting the first solid material to a first reaction with an ammonium salt solution, and sequentially subjecting the product obtained after the first reaction to a second drying and a second roasting to obtain a second solid material;

[0038] (4) performing a second reaction on the second solid material and the metal salt solution in sequence, and performing a third drying on the product obtained after the second reaction.

[0039] The molecular sieve obtained by the preparation method provided by the present invention has good reaction performance in the isomerization reaction of C8 aromatics.

[0040] Preferably, in step (1), the molar ratio of the silicon source calculated as silicon dioxide, the boron source calculated as boron trioxide and the aluminum source calculated as aluminum oxide is 20-500:0.1-1.5:1, more preferably 20-300:0.1-1:1.

[0041] Preferably, in step (1), the molar ratio of the alkali metal hydroxide calculated as hydroxide ions, the water, the template and the silicon source calculated as silicon dioxide is 0.06-0.8:10-80:0.02-0.5:1, more preferably 0.4-0.8:10-60:0.2-0.5:1.

[0042] Preferably, in step (1), the silicon source is selected from at least one of ethyl orthosilicate, silica sol, water glass, sodium silicate, solid silica gel and white carbon black.

[0043] Preferably, in step (1), the aluminum source is selected from at least one of sodium metaaluminate, aluminum oxide, aluminum hydroxide, aluminum sulfate, aluminum chloride, aluminum nitrate and sodium aluminate.

[0044] Preferably, in step (1), the boron source is selected from at least one of boric acid, sodium tetraborate and sodium metaborate.

[0045] Preferably, in step (1), the template is hexamethonium bromide and / or dibenzyldimethylammonium salt.

[0046] Preferably, in step (1), the first mixing conditions include at least: a temperature of 10-80°C, preferably 20-50°C; and a time of 4-24h, preferably 5-8h.

[0047] Preferably, in step (2), the crystallization treatment conditions include at least: a temperature of 150-200° C. and a time of 24-96 h.

[0048] Preferably, in step (2), the first drying conditions include at least: a temperature of 90-130° C. and a time of 8-20 h.

[0049] Preferably, in step (2), the conditions for the first calcination include at least: a temperature of 500-600° C. and a time of 2-6 hours.

[0050] Preferably, in step (2), the method further comprises: washing and centrifuging the crystallized product before performing the first drying.

[0051] The present invention has no special requirements for the washing and centrifuging operation methods, and can be carried out using methods known in the art. For example, the present invention washes the crystallized product multiple times with water.

[0052] Preferably, in step (3), the ammonium salt solution is ammonium chloride solution and / or ammonium nitrate solution.

[0053] Preferably, in step (3), the ratio of the molar amount of the ammonium salt solution calculated as ammonium ions to the sum of the molar amounts of boron atoms and aluminum atoms in the first solid material is 2-5:1.

[0054] Preferably, in step (3), the mass fraction of ammonium salt in the ammonium salt solution is 1-6 wt %. Exemplarily, the amount of the ammonium salt solution used is 3-10 mL relative to 1 g of the first solid material.

[0055] Preferably, in step (3), the conditions of the first reaction include at least: a temperature of 60-90° C. and a time of 0.5-2 h.

[0056] According to a particularly preferred embodiment, in step (3), the operation of the first reaction includes exchanging the first solid material with the ammonium salt solution twice.

[0057] Further preferably, in step (3), the specific operations of the two exchanges include: exchanging the first solid material with the ammonium salt solution for the first time at 60-90°C, and exchanging the product obtained after the first exchange with the aforementioned ammonium salt solution for the second time at 60-90°C.

[0058] Preferably, in step (3), the time of the first exchange and the time of the second exchange are each independently selected from 0.5-2 h.

[0059] Preferably, in step (3), the second drying conditions include at least: a temperature of 90-130° C. and a time of 8-20 h.

[0060] Preferably, in step (3), the second calcination conditions include at least: a temperature of 450-550° C. and a time of 2-6 hours.

[0061] Preferably, in step (4), the metal salt solution is selected from at least one of potassium chloride, rubidium chloride, cesium chloride, calcium chloride, strontium chloride, barium chloride, potassium nitrate, rubidium nitrate, cesium nitrate, calcium nitrate, strontium nitrate, and barium nitrate.

[0062] Preferably, in step (4), the ratio of the molar amount of the metal salt solution calculated as metal cations to the sum of the molar amounts of boron atoms and aluminum atoms in the second solid material is 0.15-2.2:1.

[0063] Preferably, in step (4), the mass fraction of the metal salt in the metal salt solution is 0.1-10 wt%.

[0064] Preferably, in step (4), the conditions of the second reaction include at least: a temperature of 20-80° C. and a time of 0.2-1 h.

[0065] Preferably, in step (4), the conditions for the third drying include at least: a temperature of 90-130° C. and a time of 8-20 h.

[0066] As mentioned above, the third aspect of the present invention provides a C8 aromatic hydrocarbon isomerization catalyst, which includes a composite carrier and metallic platinum loaded on the composite carrier, and the content of the metallic platinum is 0.05-1.0 mass% based on the total dry mass of the composite carrier; the composite carrier includes aluminum oxide and the hydrogen-type boron-containing EU-1 molecular sieve described in the first aspect, and the content of the aluminum oxide is 10-90 mass% and the content of the hydrogen-type boron-containing EU-1 molecular sieve is 10-90 mass% based on the total dry mass of the composite carrier.

[0067] Preferably, based on the total dry weight of the composite support, the content of the alumina is 30-80% by mass, and the content of the hydrogen-form boron-containing EU-1 molecular sieve is 20-70% by mass. The inventors have discovered that using a more preferred embodiment can achieve a higher yield of C8 aromatics while maintaining isomerization activity.

[0068] As mentioned above, the fourth aspect of the present invention provides a method for preparing a C8 aromatics isomerization catalyst, the method comprising the following steps:

[0069] (I) mixing the hydrogen-type boron-containing EU-1 molecular sieve described in the first aspect with alumina (I), and sequentially extruding, drying, and calcining the product obtained after the mixing (I) to obtain a composite support;

[0070] (II) mixing the composite support with a platinum compound solution for impregnation, and sequentially drying and calcining the impregnated solid material.

[0071] The amount of the hydrogenated boron-containing EU-1 molecular sieve and / or the alumina is controlled so that the content of the alumina in the composite support is 10-90% by mass and the content of the hydrogenated boron-containing EU-1 molecular sieve is 10-90% by mass on a dry basis.

[0072] The metal cation is an alkali metal cation with an atomic number ≮19 and / or an alkaline earth metal cation with an atomic number ≮19;

[0073] The amount of the platinum compound solution is controlled so that the content of metallic platinum in the catalyst based on the composite support on a dry basis is 0.05-1.0% by mass.

[0074] The present invention has no particular requirements for the extrusion molding method, as long as it can produce a strip-shaped object. Exemplarily, the extrusion molding in the present invention includes the following steps: kneading the product obtained after the contact mixing I with nitric acid, and extruding the kneaded product using a mold.

[0075] Preferably, in step (I), the concentration of nitric acid is 3-8 wt %.

[0076] Preferably, in step (I), the mixing conditions of I include at least: a temperature of 20-50° C. and a time of 0.2-2 h.

[0077] Preferably, in step (I), the drying conditions of I include at least: a temperature of 90-130° C. and a time of 8-20 h.

[0078] Preferably, in step (I), the conditions of the calcination I include at least: a temperature of 500-600° C. and a time of 2-6 hours.

[0079] Preferably, in step (II), the platinum compound solution is selected from at least one of chloroplatinic acid solution, tetraammineplatinum chloride solution, and platinum tetrachloride solution.

[0080] The present invention has no particular requirements for the amount of the platinum-containing compound solution, which can be calculated based on the configured concentration and the target platinum content of the catalyst. For example, in step (II), the amount of the platinum-containing compound solution used is 0.3-2 g relative to 1 g of the composite support.

[0081] Preferably, in step (II), the conditions of mixing II include at least: a temperature of 10-80° C., preferably 20-50° C.; and a time of 4-24 h, preferably 5-8 h.

[0082] Preferably, in step (II), the drying conditions of II at least include: a temperature of 90-130° C. and a time of 8-20 h.

[0083] Preferably, in step (II), the calcination conditions of II include at least: a temperature of 350-500° C. and a time of 2-6 hours.

[0084] Preferably, in step (II), the method further comprises: subjecting the product obtained after the roasting II to a contact reaction I with a reducing gas.

[0085] Preferably, in step (II), the conditions of the contact reaction I include at least: a temperature of 400-550° C. and a time of 1-4 h.

[0086] Preferably, in step (II), the reducing gas is hydrogen.

[0087] Preferably, in step (II), the flow rate of the reducing gas is 10-50 mL / min relative to 1 g of the product obtained after calcination II.

[0088] As mentioned above, the fifth aspect of the present invention provides a C8 aromatic hydrocarbon isomerization catalyst prepared by the method described in the fourth aspect.

[0089] As mentioned above, the sixth aspect of the present invention provides the use of the C8 aromatic hydrocarbon isomerization catalyst described in the third aspect or the fifth aspect in catalyzing the C8 aromatic hydrocarbon isomerization reaction.

[0090] The present invention will be described in detail below through examples. In the following examples, all raw materials used are commercially available unless otherwise specified.

[0091] Silicon source: silica sol, SiO2 content of 30 wt%, purchased from Zhejiang Yuda Chemical Co., Ltd.

[0092] Aluminum source: aluminum sulfate 18-hydrate, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0093] Boron source: sodium tetraborate decahydrate, purchased from Beijing Yinuokai Technology Co., Ltd.

[0094] Template agent: Hexamethonium bromide, purchased from Beijing Yinuokai Technology Co., Ltd.

[0095] C8 non-aromatic hydrocarbons: containing 21.85% by mass of ethylcyclohexane, 22.13% by mass of dimethylcyclohexane, 15.41% by mass of dimethylhexane, 28.01% by mass of trimethylcyclopentane, 11.20% by mass of trimethylpentane and 1.40% by mass of propylcyclopentane, purchased from Tianjin Petrochemical Company;

[0096] Ethylbenzene: purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0097] Meta-xylene: purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0098] o-Xylene: purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0099] Alumina: Al2O3 content of 75wt%, purchased from Beijing Yinuokai Technology Co., Ltd.

[0100] In the following examples, inductively coupled plasma spectroscopy was used to measure the molar amounts of boron atoms, silicon atoms, and aluminum atoms in the boron-containing EU-1 molecular sieve.

[0101] In the following examples, ammonium chloride, potassium chloride, cesium chloride, sodium chloride, calcium nitrate, aluminum oxide, and sodium hydroxide were all analytical grade reagents.

[0102] Preparation Example 1

[0103] This preparation provides a method for preparing hydrogen-type boron-containing EU-1 molecular sieve, which comprises:

[0104] (1) first mixing silica sol (silicon source), 1.40 g of aluminum sulfate 18hydrate (aluminum source), sodium tetraborate decahydrate (boron source), water and template agent hexamethylammonium bromide according to the molar ratio of the silicon source calculated as silicon dioxide, the boron source calculated as boron trioxide and the aluminum source calculated as aluminum oxide of 48:0.15:1, and the molar ratio of the sodium hydroxide calculated as hydroxide ions, the water, the template agent and the silicon source calculated as silicon dioxide of 0.6:60:0.5:1 to obtain a molecular sieve synthesis gel;

[0105] The first mixing temperature is room temperature and the time is 0.5h;

[0106] (2) transferring the molecular sieve synthesis gel to a reactor at 180° C. for dynamic crystallization for 96 hours to obtain a crystallized product, and washing and centrifuging the crystallized product, and then sequentially performing a first drying and a first calcination to obtain a first solid material;

[0107] The first drying temperature is 120°C and the time is 20h;

[0108] The first calcination temperature is 550°C and the time is 4h;

[0109] (3) exchanging 5 g of the first solid material with 25 g of ammonium chloride solution (with a mass fraction of ammonium chloride of 3 wt%) twice to perform a first reaction, and washing, second drying, and second calcining the product obtained after the first reaction in sequence to obtain a second solid material;

[0110] The temperature of the first reaction was 80 °C, and the time of each exchange was 2 h;

[0111] The second drying temperature is 120°C and the time is 12h;

[0112] The second calcination temperature is 550°C and the time is 4h;

[0113] (4) performing a second reaction on all the second solid material obtained above and 25 g of potassium chloride solution (wherein the mass fraction of potassium chloride is 2.1 wt%), and performing a third drying on the product obtained after the second reaction to obtain hydrogen-type boron-containing EU-1 molecular sieve S1 containing potassium ions;

[0114] The temperature of the second reaction is 35°C and the time is 1h;

[0115] The third drying temperature is 120°C and the time is 12 hours;

[0116] In the hydrogen-type boron-containing EU-1 molecular sieve S1, the ratio of the molar amount of potassium ions, the molar amount of silicon atoms, and the sum of the molar amounts of boron atoms and aluminum atoms is 0.5:20:1; and the molar ratio of the content of boron atoms to aluminum atoms is 0.15:1.

[0117] Preparation Example 2

[0118] This preparation provides a method for preparing hydrogen-type boron-containing EU-1 molecular sieve, which comprises:

[0119] (1) first mixing silica sol (silicon source), 0.46 g of aluminum sulfate 18hydrate (aluminum source), sodium tetraborate decahydrate (boron source), water and template agent hexamethylammonium bromide according to the molar ratio of the silicon source calculated as silicon dioxide, the boron source calculated as boron trioxide and the aluminum source calculated as aluminum oxide of 148:0.82:1, and the molar ratio of the sodium hydroxide calculated as hydroxide ions, the water, the template agent and the silicon source calculated as silicon dioxide of 0.6:60:0.5:1 to obtain a molecular sieve synthesis gel;

[0120] The first mixing temperature is room temperature and the time is 0.5h;

[0121] (2) transferring the molecular sieve synthesis gel to a reactor at 180° C. for dynamic crystallization for 96 hours to obtain a crystallized product, and washing and centrifuging the crystallized product, and then sequentially performing a first drying and a first calcination to obtain a first solid material;

[0122] The first drying temperature is 120°C and the time is 20h;

[0123] The first calcination temperature is 550°C and the time is 4h;

[0124] (3) exchanging 5 g of the first solid material with 25 g of ammonium chloride solution (with a mass fraction of ammonium chloride of 1.32 wt%) twice to perform a first reaction, and washing, second drying, and second calcining the product obtained after the first contact reaction in sequence to obtain a second solid material;

[0125] The temperature of the first reaction was 80 °C, and the time of each exchange was 2 h;

[0126] The second drying temperature is 120°C and the time is 12h;

[0127] The second calcination temperature is 550°C and the time is 4h;

[0128] (4) performing a second reaction on all the second solid material obtained above and 25 g of cesium chloride solution (wherein the mass fraction of cesium chloride is 1.95 wt%), and performing a third drying on the product obtained after the second reaction to obtain hydrogen-type boron-containing EU-1 molecular sieve S2 containing cesium ions;

[0129] The temperature of the second reaction is 35°C and the time is 1h;

[0130] The third drying temperature is 120°C and the time is 12 hours;

[0131] In the hydrogen-type boron-containing EU-1 molecular sieve S2, the ratio of the molar amount of cesium ions, the molar amount of silicon atoms and the sum of the molar amounts of boron atoms and aluminum atoms is 0.40:40:1, and the molar ratio of the content of boron atoms to aluminum atoms is 0.82:1.

[0132] Preparation Example 3

[0133] In this preparation example, hydrogen-type boron-containing EU-1 molecular sieve was prepared according to a method similar to that of Preparation Example 2, except that in step (4), the cesium chloride solution was replaced by an equal mass of calcium nitrate solution, wherein the mass fraction of calcium nitrate in the calcium nitrate solution was 1.20 wt%, so that the ratio of the molar amount of calcium ions to the sum of the molar amounts of boron atoms and aluminum atoms was 0.25:1.

[0134] The hydrogen-type boron-containing EU-1 molecular sieve S3 was obtained.

[0135] In the hydrogen-type boron-containing EU-1 molecular sieve S3, the ratio of the molar amount of calcium ions, the molar amount of silicon atoms and the sum of the molar amounts of boron atoms and aluminum atoms is 0.25:40:1, and the molar ratio of the content of boron atoms to aluminum atoms is 0.82:1.

[0136] Preparation Example 4

[0137] In this preparation example, hydrogen-type boron-containing EU-1 molecular sieve was prepared according to a method similar to that of Preparation Example 1, except that in step (4), the mass fraction of potassium chloride in the potassium chloride solution used was 2.60 wt%, so that the ratio of the molar amount of potassium ions to the sum of the molar amounts of boron atoms and aluminum atoms was 0.60:1.

[0138] The hydrogen-type boron-containing EU-1 molecular sieve S4 was obtained.

[0139] In the hydrogen-type boron-containing EU-1 molecular sieve S4, the ratio of the molar amount of potassium ions, the molar amount of silicon atoms and the sum of the molar amounts of boron atoms and aluminum atoms is 0.60:20:1, and the molar ratio of the content of boron atoms to aluminum atoms is 0.15:1.

[0140] Comparative Preparation Example 1 (without sodium tetraborate decahydrate)

[0141] This comparative preparation example provides a method for preparing boron-containing EU-1 molecular sieve, which comprises:

[0142] (1) first mixing silica sol (silicon source), 1.59 g of aluminum sulfate 18hydrate (aluminum source), water, and hexamethonium bromide as a template agent, according to a molar ratio of 42:0:1 of the silicon source calculated as silicon dioxide, the boron source calculated as boron trioxide, and the aluminum source calculated as aluminum oxide, and a molar ratio of 0.6:60:0.5:1 of sodium hydroxide calculated as hydroxide ions, the water, the template agent, and the silicon source calculated as silicon dioxide, to obtain a molecular sieve synthesis gel;

[0143] The first mixing temperature is room temperature and the time is 0.5h;

[0144] (2) transferring the molecular sieve synthesis gel to a reactor at 180° C. for dynamic crystallization for 96 hours to obtain a crystallized product, and washing and centrifuging the crystallized product, and then sequentially performing a first drying and a first calcination to obtain a first solid material;

[0145] The first drying temperature is 120°C and the time is 20h;

[0146] The first calcination temperature is 550°C and the time is 4h;

[0147] (3) exchanging 5 g of the first solid material with 25 g of ammonium chloride solution (with a mass fraction of ammonium chloride of 3 wt%) twice to perform a first reaction, and washing, second drying, and second calcining the product obtained after the first reaction in sequence to obtain a second solid material;

[0148] The temperature of the first reaction was 80 °C, and the time of each exchange was 2 h;

[0149] The second drying temperature is 120°C and the time is 12h;

[0150] The second calcination temperature is 550°C and the time is 4h;

[0151] (4) performing a second reaction on all the second solid materials obtained above with 25 g of potassium chloride solution (wherein the mass fraction of potassium chloride is 2.1 wt%), and performing a third drying on the product obtained after the second reaction to obtain EU-1 molecular sieve DS1 containing potassium ions;

[0152] The temperature of the second reaction is 35°C and the time is 1h;

[0153] The third drying temperature is 120°C and the time is 12 hours;

[0154] In EU-1 molecular sieve DS1, the ratio of the molar amount of potassium ions, the molar amount of silicon atoms, and the sum of the molar amounts of boron atoms and aluminum atoms is 0.5:20:1, and the molar ratio of the content of boron atoms to aluminum atoms is 0:1.

[0155] Comparative Preparation Example 2 (without the second reaction)

[0156] This preparation provides a method for preparing hydrogen-type boron-containing EU-1 molecular sieve, which comprises:

[0157] (1) first mixing silica sol (silicon source), 1.40 g of aluminum sulfate 18hydrate (aluminum source), sodium tetraborate decahydrate (boron source), water and template agent hexamethylammonium bromide according to the molar ratio of the silicon source calculated as silicon dioxide, the boron source calculated as boron trioxide and the aluminum source calculated as aluminum oxide of 48:0.15:1, and the molar ratio of the sodium hydroxide calculated as hydroxide ions, the water, the template agent and the silicon source calculated as silicon dioxide of 0.6:60:0.5:1 to obtain a molecular sieve synthesis gel;

[0158] The first mixing temperature is room temperature and the time is 0.5h;

[0159] (2) transferring the molecular sieve synthesis gel to a reactor at 180° C. for dynamic crystallization for 96 hours to obtain a crystallized product, and washing and centrifuging the crystallized product, and then sequentially performing a first drying and a first calcination to obtain a first solid material;

[0160] The first drying temperature is 120°C and the time is 20h;

[0161] The first calcination temperature is 550°C and the time is 4h;

[0162] (3) exchanging 5 g of the first solid material with 25 g of ammonium chloride solution (with an ammonium chloride mass fraction of 3 wt%) twice to perform a first reaction, and washing, second drying, and second calcining the product obtained after the first reaction in sequence to obtain a second solid material, namely, boron-containing EU-1 molecular sieve (without metal cations);

[0163] The temperature of the first reaction was 80 °C, and the time of each exchange was 2 h;

[0164] The second drying temperature is 120°C and the time is 12h;

[0165] The second calcination temperature was 550°C and the time was 4 h.

[0166] In the boron-containing EU-1 molecular sieve DS2, the ratio of the molar amount of silicon atoms to the sum of the molar amounts of boron atoms and aluminum atoms is 20:1; and the molar ratio of the content of boron atoms to aluminum atoms is 0.15:1.

[0167] Comparative Preparation Example 3

[0168] In this comparative preparation example, hydrogen-type boron-containing EU-1 molecular sieve was prepared according to a method similar to that of Preparation Example 1, except that in step (4), the mass fraction of potassium chloride in the potassium chloride solution used was 3.5 wt%, so that the ratio of the molar amount of potassium ions to the sum of the molar amounts of boron atoms and aluminum atoms was 0.8:1.

[0169] The hydrogen-type boron-containing EU-1 molecular sieve DS3 was obtained.

[0170] In the hydrogen-type boron-containing EU-1 molecular sieve DS3, the ratio of the molar amount of potassium ions, the molar amount of silicon atoms and the sum of the molar amounts of boron atoms and aluminum atoms is 0.8:20:1, and the molar ratio of the content of boron atoms to aluminum atoms is 0.15:1.

[0171] Comparative Preparation Example 4

[0172] In this comparative preparation example, hydrogen-type boron-containing EU-1 molecular sieve was prepared according to a method similar to that of Preparation Example 1, except that in step (4), the potassium chloride solution was replaced by an equal mass of sodium chloride solution, wherein the mass fraction of sodium chloride in the sodium chloride solution was 1.6 wt %, so that the ratio of the molar amount of sodium ions to the sum of the molar amounts of boron atoms and aluminum atoms was 0.5:1.

[0173] The hydrogen-type boron-containing EU-1 molecular sieve DS4 was obtained.

[0174] In the hydrogen-type boron-containing EU-1 molecular sieve DS4, the ratio of the molar amount of sodium ions, the molar amount of silicon atoms and the sum of the molar amounts of boron atoms and aluminum atoms is 0.5:20:1, and the molar ratio of the content of boron atoms to aluminum atoms is 0.15:1.

[0175] Example 1

[0176] This embodiment provides a method for preparing a C8 aromatics isomerization catalyst, the method comprising the following steps:

[0177] (I) 3 g of hydrogen-type boron-containing EU-1 molecular sieve S1 was mixed with 9.33 g of alumina (I), and then 8 mL of a 4 wt% aqueous nitric acid solution was added, kneaded, and extruded into strips. The strips were then dried (I) and calcined (I) to obtain a composite support.

[0178] The drying temperature of I is 120°C and the drying time is 4 hours;

[0179] Calcination I was performed at 550°C for 4 h;

[0180] (II) impregnating 5 g of the composite support with 3.5 g of a chloroplatinic acid solution (containing 0.4 wt % platinum) by mixing II, drying II and calcining II the impregnated solid material, and contacting the product obtained after calcining II with hydrogen (at a flow rate of 100 mL / min) to obtain a C8 aromatics isomerization catalyst A1;

[0181] The temperature of mixing II is 35°C and the time is 8h;

[0182] Drying II was performed at 120°C for 12 h;

[0183] Calcination II was performed at 450°C for 4 h;

[0184] The temperature of contact reaction I is 500° C. and the time is 2 h.

[0185] In the C8 aromatics isomerization catalyst A1, based on the total dry mass of the composite support, the content of metal platinum is 0.28 mass%; based on the total dry mass of the composite support, the content of the alumina is 70 mass%, and the content of the hydrogen-type boron-containing EU-1 molecular sieve is 30 mass%.

[0186] Example 2

[0187] In this example, a C8 aromatic hydrocarbon isomerization catalyst is prepared according to a method similar to that of Example 1, except that in step (I), the hydrogen-type boron-containing EU-1 molecular sieve S1 is replaced by an equal mass of hydrogen-type boron-containing EU-1 molecular sieve S2.

[0188] Obtaining C8 aromatic hydrocarbon isomerization catalyst A2;

[0189] In the C8 aromatics isomerization catalyst A2, based on the total dry mass of the composite support, the content of metal platinum is 0.28 mass%; based on the total dry mass of the composite support, the content of alumina is 70 mass%, and the content of hydrogen-type boron-containing EU-1 molecular sieve is 30 mass%.

[0190] Example 3

[0191] In this example, a C8 aromatic hydrocarbon isomerization catalyst is prepared according to a method similar to that of Example 1, except that in step (I), the hydrogen-type boron-containing EU-1 molecular sieve S1 is replaced by an equal mass of hydrogen-type boron-containing EU-1 molecular sieve S3.

[0192] Obtain C8 aromatic hydrocarbon isomerization catalyst A3.

[0193] In the C8 aromatics isomerization catalyst A3, based on the total dry mass of the composite support, the content of metal platinum is 0.28 mass%; based on the total dry mass of the composite support, the content of alumina is 70 mass%, and the content of hydrogen-type boron-containing EU-1 molecular sieve is 30 mass%.

[0194] Example 4

[0195] This embodiment prepares a method for isomerization catalyst of C8 aromatics in a manner similar to that of Example 1, except that in step (I), hydrogen-type boron-containing EU-1 molecular sieve S1 is replaced by an equal mass of hydrogen-type boron-containing EU-1 molecular sieve S4.

[0196] Obtain C8 aromatic hydrocarbon isomerization catalyst A4.

[0197] In the C8 aromatics isomerization catalyst A4, based on the total dry mass of the composite support, the content of metal platinum is 0.28 mass%; based on the total dry mass of the composite support, the content of alumina is 70 mass%, and the content of hydrogen-type boron-containing EU-1 molecular sieve is 30 mass%.

[0198] Example 5

[0199] This example is a method for preparing a C8 aromatic hydrocarbon isomerization catalyst in a manner similar to that of Example 1, except that in step (3), 1 g of alumina is used.

[0200] Obtain C8 aromatic hydrocarbon isomerization catalyst A5.

[0201] In the C8 aromatics isomerization catalyst A5, based on the total dry mass of the composite support, the content of metal platinum is 0.28 mass%; based on the total dry mass of the composite support, the content of alumina is 20 mass%, and the content of hydrogen-type boron-containing EU-1 molecular sieve is 80 mass%.

[0202] Comparative Example 1

[0203] In this comparative example, a C8 aromatic hydrocarbon isomerization catalyst was prepared in a manner similar to that of Example 1, except that in step (I), an equal mass of hydrogen-type boron-containing EU-1 molecular sieve DS1 was used to replace hydrogen-type boron-containing EU-1 molecular sieve S1.

[0204] Obtain C8 aromatic hydrocarbon isomerization catalyst DA1.

[0205] In the C8 aromatics isomerization catalyst DA1, based on the total dry mass of the composite support, the content of metal platinum is 0.28 mass%; based on the total dry mass of the composite support, the content of alumina is 70 mass%, and the content of EU-1 molecular sieve is 30 mass%.

[0206] Comparative Example 2

[0207] In this comparative example, a C8 aromatic hydrocarbon isomerization catalyst is prepared in a manner similar to that of Example 1, except that in step (I), an equal mass of hydrogen-type boron-containing EU-1 molecular sieve DS2 is used to replace hydrogen-type boron-containing EU-1 molecular sieve S1.

[0208] Obtain C8 aromatic hydrocarbon isomerization catalyst DA2.

[0209] In the C8 aromatics isomerization catalyst DA2, based on the total dry mass of the composite support, the content of metal platinum is 0.28 mass%; based on the total dry mass of the composite support, the content of alumina is 70 mass%, and the content of hydrogen-type boron-containing EU-1 molecular sieve is 30 mass%.

[0210] Comparative Example 3

[0211] In this comparative example, a C8 aromatic hydrocarbon isomerization catalyst is prepared according to the method of Example 1, except that in step (I), an equal mass of hydrogen-type boron-containing EU-1 molecular sieve DS3 is used to replace the hydrogen-type boron-containing EU-1 molecular sieve S1.

[0212] Obtain C8 aromatic hydrocarbon isomerization catalyst DA3.

[0213] In the C8 aromatics isomerization catalyst DA3, based on the total dry mass of the composite support, the content of metal platinum is 0.28 mass%; based on the total dry mass of the composite support, the content of the alumina is 70 mass%, and the content of the hydrogen-type boron-containing EU-1 molecular sieve is 30 mass%.

[0214] Comparative Example 4

[0215] In this comparative example, a C8 aromatic hydrocarbon isomerization catalyst is prepared according to the method of Example 1, except that in step (I), an equal mass of hydrogen-type boron-containing EU-1 molecular sieve DS4 is used to replace the hydrogen-type boron-containing EU-1 molecular sieve S1.

[0216] Obtain C8 aromatic hydrocarbon isomerization catalyst DA4.

[0217] In the C8 aromatics isomerization catalyst DA4, based on the total dry mass of the composite support, the content of metal platinum is 0.28 mass%; based on the total dry mass of the composite support, the content of the alumina is 70 mass%, and the content of the hydrogen-type boron-containing EU-1 molecular sieve is 30 mass%.

[0218] Comparative Example 5

[0219] In this comparative example, a C8 aromatic hydrocarbon isomerization catalyst was prepared according to the method of Example 1, except that in step (I), 0.35 g of aluminum oxide was used.

[0220] Obtain C8 aromatic hydrocarbon isomerization catalyst DA5.

[0221] In the C8 aromatics isomerization catalyst DA5, based on the total dry mass of the composite support, the content of metal platinum is 0.28 mass%; based on the total dry mass of the composite support, the content of alumina is 8 mass%, and the content of hydrogen-type boron-containing EU-1 molecular sieve is 92 mass%.

[0222] Comparative Example 6

[0223] In this comparative example, a C8 aromatic hydrocarbon isomerization catalyst was prepared according to the method of Example 1, except that in step (II), the platinum content in the chloroplatinic acid used was 2.15 wt%.

[0224] Obtain C8 aromatic hydrocarbon isomerization catalyst DA6.

[0225] In the C8 aromatics isomerization catalyst DA6, based on the total dry mass of the composite support, the content of metal platinum is 1.5 mass%; based on the total dry mass of the composite support, the content of alumina is 70 mass%, and the content of hydrogen-type boron-containing EU-1 molecular sieve is 30 mass%.

[0226] Test Case

[0227] The catalytic performance of the C8 aromatics isomerization catalysts prepared in the examples and comparative examples was evaluated, and the isomerization activity and C8 aromatics yield were calculated. The specific results are shown in Table 1.

[0228] The evaluation method is as follows: 2 g of the C8 aromatic isomerization catalyst prepared above is loaded on a continuous fixed-bed small-scale hydrogenation device, and the reaction raw materials are introduced to carry out the C8 aromatic isomerization reaction; wherein the raw material composition is: 6.87 mass% of C8 non-aromatic hydrocarbons, 16.70 mass% of ethylbenzene, 0.41 mass% of p-xylene, 54.25 mass% of m-xylene, and 21.77 mass% of o-xylene; the reaction conditions are: reaction temperature of 370°C, reaction pressure of 0.6 MPa, hydrogen / hydrocarbon molar ratio of 6, and raw material mass space velocity of 6 h -1 .

[0229] The reaction materials and products were analyzed by Agilent 7890A gas chromatography using an HP-WAX capillary column, 60m×0.25mm×0.5μm, and an FID detector. The analysis results were quantified by the area normalization method.

[0230] The calculation formula of isomerization activity is: (content of p-xylene in the product / total xylene content in the product) × 100%;

[0231] The calculation formula for the yield of C8 aromatics is: (total C8 aromatics content in the product / total C8 aromatics content in the raw material) × 100%.

[0232] Table 1

[0233] Example No. Isomerization activity, % Yield of C8 aromatics, % Example 1 23.94 84.7 Example 2 24.02 91.7 Example 3 23.96 92.3 Example 4 23.86 85.1 Example 5 23.96 81.7 Comparative Example 1 23.58 78.6 Comparative Example 2 23.33 73.5 Comparative Example 3 16.88 93.8 Comparative Example 4 23.35 79.3 Comparative Example 5 23.88 62.74 Comparative Example 6 23.89 64.53

[0234] It can be seen from the results in Table 1 that the C8 aromatics isomerization catalyst provided by the present invention is used to catalyze the C8 aromatics isomerization reaction, which can take into account both the isomerization activity and the C8 aromatics yield.

[0235] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A hydrogen-type boron-containing EU-1 molecular sieve, characterized in that: The molecular sieve contains metal cations; in the hydrogen-type boron-containing EU-1 molecular sieve, the ratio of the molar amount of the metal cations, the molar amount of silicon atoms, and the sum of the molar amounts of boron atoms and aluminum atoms is 0.05-0.7:10-100:1, and the molar ratio of the boron atoms to the aluminum atoms is 0.1-1.5:1; The metal cation is K + and / or Cs + .

2. The hydrogen-type boron-containing EU-1 molecular sieve according to claim 1, wherein In the hydrogen-type boron-containing EU-1 molecular sieve, the ratio of the molar amount of the metal cations, the molar amount of the silicon atoms, and the sum of the molar amounts of the boron atoms and the aluminum atoms is 0.05-0.5:10-60:

1.

3. The hydrogen-type boron-containing EU-1 molecular sieve according to claim 1 or 2, wherein In the hydrogen-type boron-containing EU-1 molecular sieve, the molar ratio of the boron atoms to the aluminum atoms is 0.1-1:

1.

4. A method for preparing the hydrogen-type boron-containing EU-1 molecular sieve according to any one of claims 1 to 3, characterized in that: The method includes: (1) first mixing a silicon source, an aluminum source, a boron source, an alkali metal hydroxide, water, and a template agent to obtain a molecular sieve synthesis gel; (2) crystallizing the molecular sieve synthesis gel to obtain a crystallized product, and sequentially performing a first drying and a first calcination on the crystallized product to obtain a first solid material; (3) sequentially subjecting the first solid material to a first reaction with an ammonium salt solution, and sequentially subjecting the product obtained after the first reaction to a second drying and a second roasting to obtain a second solid material; (4) performing a second reaction on the second solid material and the metal salt solution in sequence, and performing a third drying on the product obtained after the second reaction.

5. The method according to claim 4, wherein In step (1), the molar ratio of the silicon source calculated as silicon dioxide, the boron source calculated as boron trioxide and the aluminum source calculated as aluminum oxide is 20-500:0.1-1.5:

1.

6. The method according to claim 5, wherein: In step (1), the molar ratio of the silicon source calculated as silicon dioxide, the boron source calculated as boron trioxide and the aluminum source calculated as aluminum oxide is 20-300:0.1-1:

1.

7. The method according to claim 4 or 5, wherein: In step (1), the molar ratio of the alkali metal hydroxide calculated as hydroxide ions, the water, the template and the silicon source calculated as silicon dioxide is 0.06-0.8:10-80:0.02-0.5:

1.

8. The method according to claim 4 or 5, wherein: In step (1), the molar ratio of the alkali metal hydroxide calculated as hydroxide ions, the water, the template and the silicon source calculated as silicon dioxide is 0.4-0.8:10-60:0.2-0.5:

1.

9. The method according to claim 4 or 5, wherein: In step (1), the silicon source is selected from at least one of ethyl orthosilicate, silica sol, water glass, sodium silicate, solid silica gel and white carbon black.

10. The method according to claim 4 or 5, wherein: In step (1), the aluminum source is selected from at least one of sodium metaaluminate, aluminum oxide, aluminum hydroxide, aluminum sulfate, aluminum chloride, aluminum nitrate and sodium aluminate.

11. The method according to claim 4 or 5, wherein: In step (1), the boron source is selected from at least one of boric acid, sodium tetraborate, and sodium metaborate.

12. The method according to claim 4 or 5, wherein: In step (1), the template is hexamethonium bromide and / or dibenzyldimethylammonium salt.

13. The method according to claim 4 or 5, wherein: In step (1), the first mixing conditions include at least: a temperature of 10-80° C. and a time of 0.1-12 h.

14. The method according to claim 4 or 5, wherein: In step (1), the first mixing conditions include at least: a temperature of 20-50° C. and a time of 0.2-2 h.

15. The method according to claim 4 or 5, wherein: In step (2), the crystallization treatment conditions include at least: a temperature of 150-200° C. and a time of 24-96 hours.

16. The method according to claim 4 or 5, wherein: In step (2), the first drying conditions include at least: a temperature of 90-130° C. and a time of 8-20 hours.

17. The method according to claim 4 or 5, wherein: In step (2), the first calcination conditions include at least: a temperature of 500-600° C. and a time of 2-6 hours.

18. The method according to claim 4 or 5, wherein: In step (3), the ammonium salt solution is ammonium chloride solution and / or ammonium nitrate solution.

19. The method according to claim 4 or 5, wherein: In step (3), the ratio of the molar amount of the ammonium salt solution calculated as ammonium ions to the sum of the molar amounts of boron atoms and aluminum atoms in the first solid material is 2-5:

1.

20. The method according to claim 4 or 5, wherein In step (3), the conditions of the first reaction include at least: a temperature of 60-90° C. and a time of 0.5-2 h.

21. The method according to claim 4 or 5, wherein The second drying conditions at least include: a temperature of 90-130° C. and a time of 8-20 hours.

22. The method according to claim 4 or 5, wherein The second calcination conditions at least include: a temperature of 450-550° C. and a time of 2-6 hours.

23. The method according to claim 4 or 5, wherein: In step (4), the metal salt solution is selected from at least one of potassium chloride, cesium chloride, potassium nitrate, and cesium nitrate.

24. The method according to claim 4 or 5, wherein In step (4), the ratio of the molar amount of the metal salt solution calculated as metal cations to the sum of the molar amounts of boron atoms and aluminum atoms in the second solid material is 0.15-2.2:

1.

25. The method according to claim 4 or 5, wherein In step (4), the conditions of the second reaction include at least: a temperature of 20-80° C. and a time of 0.2-1 h.

26. The method according to claim 4 or 5, wherein In step (4), the conditions for the third drying include at least: a temperature of 90-130° C. and a time of 8-20 h.

27. A C8 aromatic hydrocarbon isomerization catalyst, characterized in that: The catalyst includes a composite carrier and metallic platinum supported on the composite carrier, wherein the content of the metallic platinum is 0.05-1.0 mass % based on the total dry mass of the composite carrier; the composite carrier includes aluminum oxide and the hydrogen-type boron-containing EU-1 molecular sieve according to any one of claims 1 to 3, wherein the content of the aluminum oxide is 10-90 mass % and the content of the hydrogen-type boron-containing EU-1 molecular sieve is 10-90 mass % based on the total dry mass of the composite carrier.

28. The C8 aromatics isomerization catalyst according to claim 27, wherein: Based on the total dry mass of the composite carrier, the content of the alumina is 30-80% by mass, and the content of the hydrogen-type boron-containing EU-1 molecular sieve is 20-70% by mass.

29. A method for preparing a C8 aromatic hydrocarbon isomerization catalyst, characterized in that: The method comprises the following steps: (I) mixing the hydrogen-type boron-containing EU-1 molecular sieve according to any one of claims 1 to 3 with alumina for I, and sequentially extruding, drying, and calcining the product obtained after the mixing for I to obtain a composite support; (II) mixing the composite support with a platinum compound solution for impregnation, and sequentially drying and calcining the impregnated solid material. The amount of the hydrogenated boron-containing EU-1 molecular sieve and / or the alumina is controlled so that the content of the alumina in the composite support is 10-90% by mass and the content of the hydrogenated boron-containing EU-1 molecular sieve is 10-90% by mass on a dry basis. The amount of the platinum compound solution is controlled so that the content of metallic platinum in the catalyst based on the composite support on a dry basis is 0.05-1.0% by mass.

30. The method according to claim 29, wherein In step (I), the drying conditions include at least: a temperature of 90-130° C. and a time of 8-20 h.

31. The method according to claim 29, wherein In step (I), the conditions of calcination I include at least: a temperature of 500-600° C. and a time of 2-6 hours.

32. The method according to claim 29 or 30, wherein In step (II), the platinum compound solution is selected from at least one of chloroplatinic acid solution, tetraammineplatinum chloride solution, and platinum tetrachloride solution.

33. The method according to claim 29 or 30, wherein In step (II), the mixing conditions of II include at least: a temperature of 10-80° C. and a time of 4-24 h.

34. The method according to claim 29 or 30, wherein In step (II), the mixing conditions of II include at least: a temperature of 20-50° C. and a time of 5-8 h.

35. The method according to claim 29 or 30, wherein In step (II), the drying conditions of II at least include: a temperature of 90-130° C. and a time of 8-20 h.

36. The method according to claim 29 or 30, wherein In step (II), the calcination conditions of II include at least: a temperature of 350-500° C. and a time of 2-6 hours.

37. The method according to claim 29 or 30, wherein In step (II), the method further comprises: subjecting the product obtained after the roasting II to a contact reaction I with a reducing gas.

38. The method of claim 37, wherein: In step (II), the conditions of the contact reaction I include at least: a temperature of 400-550° C. and a time of 1-4 hours.

39. The method of claim 37, wherein: In step (II), the reducing gas is hydrogen.

40. A C8 aromatic hydrocarbon isomerization catalyst prepared by the method described in any one of claims 29 to 39.

41. Use of the C8 aromatic hydrocarbon isomerization catalyst according to claim 27 or 40 in catalyzing the isomerization reaction of C8 aromatic hydrocarbons.