Hydrogen-type boron-containing ZSM-5 molecular sieve and preparation method thereof, xylene isomerization catalyst and preparation method and application thereof

Abstract

The present invention relates to the technical field of aromatic hydrocarbon isomerization catalysts, and discloses a hydrogen-type boron-containing ZSM-5 molecular sieve and a preparation method thereof, a xylene 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 ZSM-5 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 0.05-0.7:10-200:1, and the molar ratio of the content of boron atoms to aluminum atoms is 0.1-1.5:1. The hydrogen-type boron-containing ZSM-5 molecular sieve provided by the present invention can effectively reduce the occurrence of disproportionation side reactions while maintaining a high xylene isomerization activity, thereby achieving a further increase in xylene yield.

Description

Technical Field

[0001] The present invention relates to the technical field of aromatic hydrocarbon isomerization catalysts, and in particular to a hydrogen-type boron-containing ZSM-5 molecular sieve and a preparation method thereof, a xylene 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 process. 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] US4482773A discloses a ZSM-5 catalyst loaded with Pt and Mg, US4874731A discloses a ZSM-5 catalyst loaded with Pt and Bi, and US4939110A discloses a ZSM-5 catalyst loaded with Pt and Pb.

[0008] CN1102360A discloses an alkyl aromatic hydrocarbon isomerization catalyst, which uses a composite zeolite composed of high-silicon ZSM-5 zeolite and mordenite as an active component and is loaded with precious metals, and can increase the ethylbenzene conversion rate to about 60%.

[0009] Although the aforementioned ZSM-5 catalysts can complete the xylene isomerization reaction, the ethylbenzene conversion rate is low, and the catalyst activity and selectivity need to be improved.

[0010] CN103418422A discloses an alkyl aromatic isomerization catalyst and a preparation method thereof. The method comprises treating a catalyst containing ZSM-5 and ZSM-11 molecular sieves with water or a C2-C4 alcohol to improve the dealkylation performance of the catalyst.

[0011] CN104338552A discloses a sulfurization modification method for a xylene isomerization catalyst. This method can inhibit the disproportionation side reaction and improve the xylene yield by introducing a sulfur-containing compound to react with the acid center of the catalyst.

[0012] However, the aforementioned methods all treat the entire catalyst after molding. However, since there is still a certain amount of alumina carrier in the catalyst, the carrier will also be treated during the treatment process, thereby reducing the treatment efficiency of the active center of the molecular sieve and making it difficult to accurately control the degree of treatment. The modification of the carrier may even block the molecular sieve pores, resulting in an adverse effect on the catalytic activity. Summary of the Invention

[0013] The purpose of the present invention is to overcome the defects of the prior art in that the xylene isomerization reaction has poor activity and is prone to disproportionation side reactions, resulting in low xylene yield.

[0014] In order to achieve the above-mentioned object, the first aspect of the present invention provides a hydrogen-type boron-containing ZSM-5 molecular sieve, which 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 ZSM-5 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 0.05-0.7:10-200:1, and the molar ratio of the boron atoms to the aluminum atoms is 0.1-1.5:1.

[0015] The second aspect of the present invention provides a method for preparing the hydrogen-type boron-containing ZSM-5 molecular sieve described in the first aspect, the method comprising:

[0016] (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;

[0017] (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;

[0018] (3) performing a first reaction on the first solid material and an ammonium salt solution, and sequentially performing a second drying and a second calcination on the product obtained after the first reaction to obtain a second solid material;

[0019] (4) performing a second reaction on the second solid material and the metal salt solution, and performing a third drying on the product obtained after the second reaction.

[0020] The third aspect of the present invention provides a xylene isomerization catalyst, which includes a composite support and metallic platinum loaded on the composite support, and the content of the metallic platinum is 0.02-0.5 mass% based on the total dry mass of the composite support; the composite support includes aluminum oxide and the hydrogen-type boron-containing ZSM-5 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 ZSM-5 molecular sieve is 10-90 mass% based on the total dry mass of the composite support.

[0021] A fourth aspect of the present invention provides a method for preparing a xylene isomerization catalyst, the method comprising the following steps:

[0022] (I) contacting and mixing the hydrogen-type boron-containing ZSM-5 molecular sieve described in the first aspect with alumina I, and sequentially extruding, drying, and calcining I the product obtained after the contacting and mixing I to obtain a composite support;

[0023] (II) contacting and mixing the composite support with a platinum compound solution to impregnate the composite support, and sequentially drying and calcining the impregnated solid material.

[0024] wherein the amount of the hydrogenated boron-containing ZSM-5 molecular sieve and / or the alumina is controlled so that the content of the alumina in the composite support on a dry basis is 10-90% by mass and the content of the hydrogenated boron-containing ZSM-5 molecular sieve is 10-90% by mass;

[0025] 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;

[0026] 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 0.02-0.5% by mass.

[0027] The fifth aspect of the present invention provides a xylene isomerization catalyst prepared by the method described in the fourth aspect.

[0028] The sixth aspect of the present invention provides use of the xylene isomerization catalyst described in the third aspect or the fifth aspect in catalyzing a toluene isomerization reaction.

[0029] The xylene isomerization catalyst formed by using the hydrogen-type boron-containing molecular sieve ZSM-5 provided by the present invention can effectively reduce the occurrence of disproportionation side reactions while maintaining high xylene isomerization activity, thereby improving the xylene yield. DETAILED DESCRIPTION

[0030] 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.

[0031] In the present invention, unless otherwise specified, normal temperature or room temperature refers to 25±2°C.

[0032] In the present invention, unless otherwise stated, the pressures mentioned are gauge pressures.

[0033] As described above, the first aspect of the present invention provides a hydrogen-type boron-containing ZSM-5 molecular sieve, which 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 ZSM-5 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 0.05-0.7:10-200:1, and the molar ratio of the boron atoms to the aluminum atoms is 0.1-1.5:1.

[0034] Preferably, the metal cation is selected from K + , Rb + 、Cs + , Ca 2+ 、Sr 2+ 、Ba 2+ At least one of .

[0035] Preferably, the metal cation is K + , Ca 2+ 、Cs + The inventors have found that in the specific embodiment under this preferred case, the obtained molecular sieve has better reaction performance in the isomerization reaction of C8 aromatics.

[0036] Preferably, in the hydrogen-type boron-containing ZSM-5 molecular sieve, the ratio of the molar amount of the metal cations to the molar amount of the silicon atoms to the sum of the molar amounts of the boron atoms and the aluminum atoms is 0.05-0.5:10-100:1. The inventors have found that in this preferred embodiment, the obtained molecular sieve has superior catalytic activity.

[0037] Preferably, in the hydrogen-type boron-containing ZSM-5 molecular sieve, the molar ratio of the boron atoms to the aluminum atoms is 0.1-1:1.

[0038] As mentioned above, the second aspect of the present invention provides a method for preparing the hydrogen-type boron-containing ZSM-5 molecular sieve described in the first aspect, the method comprising:

[0039] (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;

[0040] (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;

[0041] (3) performing a first reaction on the first solid material and an ammonium salt solution, and sequentially performing a second drying and a second calcination on the product obtained after the first reaction to obtain a second solid material;

[0042] (4) performing a second reaction on the second solid material and the metal salt solution, and performing a third drying on the product obtained after the second reaction.

[0043] The molecular sieve obtained by the preparation method provided by the present invention has good reaction performance in the xylene isomerization reaction.

[0044] 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 20-1000:0.1-1.5:1, more preferably 20-450:0.1-1:1. The inventors have found that in the specific embodiment under this preferred embodiment, the molecular sieve obtained can be used in the catalytic reaction of xylene isomerization to increase the yield of isomerized active xylene.

[0045] 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 0.06-0.5:10-50:0.02-0.2:1.

[0046] 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.

[0047] 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.

[0048] Preferably, in step (1), the aluminum source is aluminum sulfate 18-hydrate.

[0049] Preferably, in step (1), the boron source is selected from at least one of boric acid, sodium tetraborate and sodium metaborate.

[0050] Preferably, in step (1), the boron source is sodium tetraborate decahydrate.

[0051] Preferably, in step (1), the template is selected from at least one of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetramethylammonium bromide, tetraethylammonium bromide, tetrapropylammonium bromide and tetrabutylammonium bromide.

[0052] Preferably, in step (1), the first mixing conditions include at least: a temperature of 20-50° C. and a time of 0.2-2 h.

[0053] Preferably, in step (2), the conditions for the crystallization treatment include at least: a temperature of 120-190° C. and a time of 24-40 h.

[0054] Preferably, in step (2), the first drying conditions include at least: a temperature of 90-130° C. and a time of 8-20 h.

[0055] 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.

[0056] Preferably, in step (2), the method further comprises: washing and centrifuging the crystallized product before performing the first drying.

[0057] 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.

[0058] According to a particularly preferred embodiment, in step (3), the ammonium salt solution is selected from at least one of ammonium chloride solution and ammonium nitrate solution.

[0059] 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.

[0060] Preferably, in step (3), the mass fraction of the ammonium salt in the ammonium salt solution is 1-6 wt %. For example, the amount of the ammonium salt solution used is 3-10 mL relative to 1 g of the first solid material.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] Preferably, in step (3), the second drying conditions include at least: a temperature of 90-130° C. and a time of 8-20 h.

[0066] Preferably, in step (3), the second calcination conditions include at least: 450-550° C., and time of 2-6 h.

[0067] 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.

[0068] 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.

[0069] Preferably, in step (4), the mass fraction of the metal salt in the metal salt solution is 0.1-10 wt%.

[0070] 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.

[0071] 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.

[0072] As described above, the third aspect of the present invention provides a xylene isomerization catalyst, which includes a composite support and metallic platinum loaded on the composite support, and the content of the metallic platinum is 0.02-0.5 mass% based on the total dry mass of the composite support; the composite support includes aluminum oxide and the hydrogen-type boron-containing ZSM-5 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 ZSM-5 molecular sieve is 10-90 mass% based on the total dry mass of the composite support.

[0073] 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-type boron-containing ZSM-5 molecular sieve is 20-70% by mass. The inventors have found that using this preferred embodiment, the obtained xylene isomerization catalyst has a higher xylene yield.

[0074] As mentioned above, the fourth aspect of the present invention provides a method for preparing a xylene isomerization catalyst, the method comprising the following steps:

[0075] (I) contacting and mixing the hydrogen-type boron-containing ZSM-5 molecular sieve described in the first aspect with alumina I, and sequentially extruding, drying, and calcining I the product obtained after the contacting and mixing I to obtain a composite support;

[0076] (II) contacting and mixing the composite support with a platinum compound solution to impregnate the composite support, and sequentially drying and calcining the impregnated solid material.

[0077] wherein the amount of the hydrogenated boron-containing ZSM-5 molecular sieve and / or the alumina is controlled so that the content of the alumina in the composite support on a dry basis is 10-90% by mass and the content of the hydrogenated boron-containing ZSM-5 molecular sieve is 10-90% by mass;

[0078] 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;

[0079] 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 0.02-0.5% by mass.

[0080] 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.

[0081] Preferably, in step (I), the concentration of nitric acid is 3-8 wt %.

[0082] Preferably, in step (I), the conditions of the contact mixing I include at least: a temperature of 20-50° C. and a time of 0.2-2 h.

[0083] 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.

[0084] Preferably, in step (I), the conditions of calcination I include at least: a temperature of 500-600° C. and a time of 2-6 hours.

[0085] 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.

[0086] 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.

[0087] Preferably, in step (II), the conditions of the contact mixing II include at least: a temperature of 10-80°C, more preferably 20-50°C; and a time of 4-24h, more preferably 5-8h.

[0088] Preferably, in step (II), the drying conditions of II at least include: a temperature of 90-130° C. and a time of 8-12 h.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] Preferably, in step (II), the reducing gas is hydrogen.

[0093] 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.

[0094] As mentioned above, the fifth aspect of the present invention provides a xylene isomerization catalyst prepared by the method described in the fourth aspect.

[0095] As mentioned above, the sixth aspect of the present invention provides the use of the xylene isomerization catalyst described in the third aspect or the fifth aspect in catalyzing a toluene isomerization reaction.

[0096] 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.

[0097] Silicon source: silica sol, SiO2 content of 30 wt%, purchased from Zhejiang Yuda Chemical Co., Ltd.

[0098] Aluminum source: aluminum sulfate 18-hydrate, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0099] Boron source: sodium tetraborate decahydrate, purchased from Beijing Yinuokai Technology Co., Ltd.

[0100] Template agent: tetrapropylammonium hydroxide, purchased from Beijing Yinuokai Technology Co., Ltd.;

[0101] Ethylbenzene: purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0102] Meta-xylene: purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0103] o-Xylene: purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0104] Alumina: Al2O3 content of 75wt% was purchased from Beijing Yinuokai Technology Co., Ltd.

[0105] 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 ZSM-5 molecular sieve.

[0106] In the following examples, ammonium chloride, rubidium chloride, potassium chloride, cesium chloride, sodium chloride, calcium nitrate, and sodium hydroxide are all analytical grade reagents.

[0107] Preparation Example 1

[0108] This preparation example provides a method for preparing hydrogen-type boron-containing ZSM-5 molecular sieve, which comprises:

[0109] (1) silica sol (silicon source), 1.12 g of aluminum sulfate 18hydrate (aluminum source), sodium tetraborate decahydrate (boron source), sodium hydroxide, water and a template tetrapropylammonium hydroxide aqueous solution (the mass fraction of tetrapropylammonium hydroxide is 25 wt %) are first mixed 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 60:0.15:1, and the molar ratio of the sodium hydroxide calculated as hydroxide ions, the water, the template and the silicon source calculated as silicon dioxide of 0.06:10:0.02:1 to obtain a molecular sieve synthesis gel;

[0110] The first mixing temperature is room temperature and the time is 0.5h;

[0111] (2) transferring the molecular sieve synthesis gel to a reactor at 150° C. for dynamic crystallization for 30 hours to obtain a crystallized product, washing and centrifuging the crystallized product, and then sequentially performing a first drying and a first calcination to obtain a first solid material;

[0112] The first drying temperature is 120°C and the time is 20h;

[0113] The first calcination temperature is 550°C and the time is 4h;

[0114] (3) exchanging 5 g of the first solid material with 25 g of ammonium chloride solution (with a mass fraction of ammonium chloride of 2 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;

[0115] The temperature of the first reaction was 80 °C, and the time of each exchange was 2 h;

[0116] The second drying temperature is 120°C and the time is 12h;

[0117] The second calcination temperature is 550°C and the time is 4h;

[0118] (4) performing a second reaction on all the second solid materials obtained above and 25 g of potassium chloride solution (wherein the mass fraction of potassium chloride is 1.55 wt%), and performing a third drying on the product obtained after the second reaction to obtain hydrogen-type boron-containing ZSM-5 molecular sieve S1 containing potassium ions;

[0119] The temperature of the second reaction is 35°C and the time is 1h;

[0120] The third drying temperature is 120°C and the time is 12 hours;

[0121] In the hydrogen-type boron-containing ZSM-5 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 0.45:26:1; and the molar ratio of the content of boron atoms to aluminum atoms is 0.15:1.

[0122] Preparation Example 2

[0123] This preparation example provides a method for preparing hydrogen-type boron-containing ZSM-5 molecular sieve, which comprises:

[0124] (1) silica sol (silicon source), 0.35 g of aluminum sulfate 18hydrate (aluminum source), sodium tetraborate decahydrate (boron source), sodium hydroxide, water and a template tetrapropylammonium hydroxide aqueous solution (the mass fraction of tetrapropylammonium hydroxide is 25 wt %) are first mixed 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 220:0.82:1, and the molar ratio of the sodium hydroxide calculated as hydroxide ions, the water, the template and the silicon source calculated as silicon dioxide of 0.06:10:0.02:1 to obtain a molecular sieve synthesis gel;

[0125] The first mixing temperature is room temperature and the time is 0.5h;

[0126] (2) transferring the molecular sieve synthesis gel to a reactor at 150° C. for dynamic crystallization for 30 hours to obtain a crystallized product, washing and centrifuging the crystallized product, and then sequentially performing a first drying and a first calcination to obtain a first solid material;

[0127] The first drying temperature is 120°C and the time is 20h;

[0128] The first calcination temperature is 550°C and the time is 4h;

[0129] (3) exchanging 5 g of the first solid material with 25 g of ammonium chloride solution (with a mass fraction of ammonium chloride of 1.2 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;

[0130] The temperature of the first reaction was 80 °C, and the time of each exchange was 2 h;

[0131] The second drying temperature is 120°C and the time is 12h;

[0132] The second calcination temperature is 550°C and the time is 4h;

[0133] (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 0.65 wt%), and performing a third drying on the product obtained after the second reaction to obtain hydrogen-type boron-containing ZSM-5 molecular sieve S2 containing cesium ions;

[0134] The temperature of the second reaction is 35°C and the time is 1h;

[0135] The third drying temperature is 120°C and the time is 12 hours;

[0136] In the hydrogen-type boron-containing ZSM-5 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 0.20:60:1; and the molar ratio of the content of boron atoms to aluminum atoms is 0.82:1.

[0137] Preparation Example 3

[0138] In this preparation example, hydrogen-type boron-containing ZSM-5 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 0.79 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.

[0139] The hydrogen-type boron-containing ZSM-5 molecular sieve S3 was obtained.

[0140] In the hydrogen-type boron-containing ZSM-5 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 0.25:60:1; and the molar ratio of the content of boron atoms to aluminum atoms is 0.82:1.

[0141] Preparation Example 4

[0142] In this preparation example, hydrogen-type boron-containing ZSM-5 molecular sieve is prepared according to a method similar to that of Preparation Example 2, except that in step (4), the cesium chloride solution is replaced by an equal mass of rubidium chloride solution, wherein the mass fraction of rubidium chloride in the rubidium chloride solution is 1.20 wt%, so that the ratio of the molar amount of rubidium ions to the sum of the molar amounts of boron atoms and aluminum atoms is 0.20:1.

[0143] The hydrogen-type boron-containing ZSM-5 molecular sieve S4 was obtained.

[0144] In the hydrogen-type boron-containing ZSM-5 molecular sieve S4, the ratio of the molar amount of rubidium ions, the molar amount of silicon atoms, and the sum of the molar amounts of boron atoms and aluminum atoms is 0.20:60:1; and the molar ratio of the content of boron atoms to aluminum atoms is 0.82:1.

[0145] Preparation Example 5

[0146] In this preparation example, hydrogen-type boron-containing ZSM-5 molecular sieve was prepared according to a method similar to that of Preparation Example 2, except that in step (4), the mass fraction of cesium chloride in the cesium chloride solution used was 1.95 wt%, so that the ratio of the molar amount of cesium ions to the sum of the molar amounts of boron atoms and aluminum atoms was 0.60:1.

[0147] The hydrogen-type boron-containing ZSM-5 molecular sieve S5 was obtained.

[0148] In the hydrogen-type boron-containing ZSM-5 molecular sieve S5, 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 0.60:60:1; and the molar ratio of the content of boron atoms to aluminum atoms is 0.82:1.

[0149] Comparative Preparation Example 1 (without sodium tetraborate decahydrate)

[0150] This comparative preparation example provides a method for preparing ZSM-5 molecular sieve, which comprises:

[0151] (1) first mixing silica sol (silicon source), 1.22 g of aluminum sulfate 18hydrate (aluminum source), sodium hydroxide, water and a template tetrapropylammonium hydroxide aqueous solution (the mass fraction of tetrapropylammonium hydroxide is 25 wt %) according to a molar ratio of 55:0:1 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 0.06:10:0.02:1 of the sodium hydroxide calculated as hydroxide ions, the water, the template and the silicon source calculated as silicon dioxide to obtain a molecular sieve synthesis gel;

[0152] The first mixing temperature is room temperature and the time is 0.5h;

[0153] (2) transferring the molecular sieve synthesis gel to a reactor at 150° C. for dynamic crystallization for 30 hours to obtain a crystallized product, washing and centrifuging the crystallized product, and then sequentially performing a first drying and a first calcination to obtain a first solid material;

[0154] The first drying temperature is 120°C and the time is 20h;

[0155] The first calcination temperature is 550°C and the time is 4h;

[0156] (3) exchanging 5 g of the first solid material with 25 g of ammonium chloride solution (with a mass fraction of ammonium chloride of 2 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;

[0157] The temperature of the first reaction was 80 °C, and the time of each exchange was 2 h;

[0158] The second drying temperature is 120°C and the time is 12h;

[0159] The second calcination temperature is 550°C and the time is 4h;

[0160] (4) performing a second reaction on all the second solid materials obtained above and 25 g of a potassium chloride solution (wherein the mass fraction of potassium chloride is 1.55 wt%), and performing a third drying on the product obtained after the second reaction to obtain a ZSM-5 molecular sieve DS1 containing potassium ions;

[0161] The temperature of the second reaction is 35°C and the time is 1h;

[0162] The third drying temperature is 120°C and the time is 12 hours;

[0163] In the ZSM-5 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 0.45:26:1, and the molar ratio of the content of boron atoms to aluminum atoms is 0:1.

[0164] Comparative Preparation Example 2 (No Second Reaction, i.e., No Metal Cation)

[0165] This comparative preparation example provides a method for preparing a boron-containing ZSM-5 molecular sieve, the method comprising:

[0166] (1) silica sol (silicon source), 1.12 g of aluminum sulfate 18hydrate (aluminum source), sodium tetraborate decahydrate (boron source), sodium hydroxide, water and a template tetrapropylammonium hydroxide aqueous solution (the mass fraction of tetrapropylammonium hydroxide is 25 wt %) are first mixed 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 60:0.15:1, and the molar ratio of the sodium hydroxide calculated as hydroxide ions, the water, the template and the silicon source calculated as silicon dioxide of 0.06:10:0.02:1 to obtain a molecular sieve synthesis gel;

[0167] The first mixing temperature is room temperature and the time is 0.5h;

[0168] (2) transferring the molecular sieve synthesis gel to a reactor at 150° C. for dynamic crystallization for 30 hours to obtain a crystallized product, washing and centrifuging the crystallized product, and then sequentially performing a first drying and a first calcination to obtain a first solid material;

[0169] The first drying temperature is 120°C and the time is 20h;

[0170] The first calcination temperature is 550°C and the time is 4h;

[0171] (3) exchanging 5 g of the first solid material with 25 g of ammonium chloride solution (with an ammonium chloride mass fraction of 2 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 ZSM-5 molecular sieve DS2 (without metal cations);

[0172] The temperature of the first reaction was 80 °C, and the time of each exchange was 2 h;

[0173] The second drying temperature is 120°C and the time is 12h;

[0174] The second calcination temperature is 550°C and the time is 4h;

[0175] In the boron-containing ZSM-5 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 26:1; and the molar ratio of the content of boron atoms to aluminum atoms is 0.15:1.

[0176] Comparative Preparation Example 3

[0177] In this comparative preparation example, hydrogen-type boron-containing ZSM-5 molecular sieve was prepared according to a method similar to that of Preparation Example 2, except that in step (4), the mass fraction of cesium chloride in the cesium chloride solution used was 2.6 wt%, so that the ratio of the molar amount of cesium ions to the sum of the molar amounts of boron atoms and aluminum atoms was 0.80:1.

[0178] The hydrogen-type boron-containing ZSM-5 molecular sieve DS3 was obtained.

[0179] In the hydrogen-type boron-containing ZSM-5 molecular sieve DS3, 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 0.80:60:1; and the molar ratio of the content of boron atoms to aluminum atoms is 0.82:1.

[0180] Comparative Preparation Example 4

[0181] In this comparative preparation example, hydrogen-type boron-containing ZSM-5 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 sodium chloride solution, wherein the mass fraction of sodium chloride in the sodium chloride solution was 0.23 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 0.20:1.

[0182] The hydrogen-type boron-containing ZSM-5 molecular sieve DS4 was obtained.

[0183] In the hydrogen-type boron-containing ZSM-5 molecular sieve DS3, 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 0.20:60:1; and the molar ratio of the content of boron atoms to aluminum atoms is 0.82:1.

[0184] Example 1

[0185] This embodiment provides a method for preparing a xylene isomerization catalyst, which comprises the following steps:

[0186] (I) 3 g of hydrogen-type boron-containing ZSM-5 molecular sieve S1 was contacted and mixed with 2.67 g of alumina (I), and then 4 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;

[0187] The drying temperature of I is 120°C and the drying time is 4 hours;

[0188] Calcination I was performed at 550°C for 4 h;

[0189] (II) contacting and mixing the entire composite support obtained above with 3.5 g of a chloroplatinic acid solution (containing 0.4 wt% platinum) for impregnation (II), and sequentially drying (II) and calcining (II) the impregnated solid material. The product obtained after calcination (II) was then contacted and reacted with hydrogen (at a flow rate of 100 mL / min) to obtain a xylene isomerization catalyst A1.

[0190] The temperature of contact mixing II is 35°C and the time is 8h;

[0191] Drying II was performed at 120°C for 12 h;

[0192] Calcination II was performed at 450°C for 4 h;

[0193] The temperature of contact reaction I is 500° C. and the time is 2 h.

[0194] In the xylene 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 40 mass %, and the content of the hydrogen-type boron-containing ZSM-5 molecular sieve is 60 mass %.

[0195] Example 2

[0196] In this example, a xylene isomerization catalyst was prepared in a manner similar to that of Example 1, except that in step (I), the hydrogenated boron-containing ZSM-5 molecular sieve S1 was replaced with an equal mass of hydrogenated boron-containing ZSM-5 molecular sieve S2.

[0197] A xylene isomerization catalyst A2 was obtained.

[0198] In the xylene 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 the alumina is 40 mass%, and the content of the hydrogen-type boron-containing ZSM-5 molecular sieve is 60 mass%.

[0199] Example 3

[0200] In this example, a xylene isomerization catalyst was prepared in a manner similar to that of Example 1, except that in step (I), the hydrogenated boron-containing ZSM-5 molecular sieve S1 was replaced with an equal mass of hydrogenated boron-containing ZSM-5 molecular sieve S3.

[0201] A xylene isomerization catalyst A3 was obtained.

[0202] In the xylene 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 the alumina is 40 mass%, and the content of the hydrogen-type boron-containing ZSM-5 molecular sieve is 60 mass%.

[0203] Example 4

[0204] This example is a method for preparing a xylene isomerization catalyst in a manner similar to that of Example 3, except that in step (I), the hydrogen-type boron-containing ZSM-5 molecular sieve S3 is replaced by an equal mass of hydrogen-type boron-containing ZSM-5 molecular sieve S4.

[0205] A xylene isomerization catalyst A4 was obtained.

[0206] In the xylene 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 the alumina is 40 mass%, and the content of the hydrogen-type boron-containing ZSM-5 molecular sieve is 60 mass%.

[0207] Example 5

[0208] This example is a method for preparing a xylene isomerization catalyst in a manner similar to that of Example 3, except that in step (I), the hydrogen-type boron-containing ZSM-5 molecular sieve S3 is replaced by an equal mass of hydrogen-type boron-containing ZSM-5 molecular sieve S5.

[0209] A xylene isomerization catalyst A5 was obtained.

[0210] In the xylene 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 the alumina is 40 mass%, and the content of the hydrogen-type boron-containing ZSM-5 molecular sieve is 60 mass%.

[0211] Example 6

[0212] This example is a method for preparing a xylene isomerization catalyst in a manner similar to that of Example 3, except that in step (I), 1 g of alumina is used.

[0213] A xylene isomerization catalyst A6 was obtained.

[0214] In the xylene isomerization catalyst A6, 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 20 mass%, and the content of the hydrogen-type boron-containing ZSM-5 molecular sieve is 80 mass%.

[0215] Comparative Example 1

[0216] In this comparative example, a xylene isomerization catalyst was prepared in a manner similar to that of Example 3, except that in step (I), an equal mass of hydrogen-type boron-containing ZSM-5 molecular sieve DS1 was used to replace hydrogen-type boron-containing ZSM-5 molecular sieve S3.

[0217] A xylene isomerization catalyst DA1 was obtained.

[0218] In the xylene 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 the alumina is 40 mass %, and the content of the ZSM-5 molecular sieve is 60 mass %.

[0219] Comparative Example 2

[0220] In this comparative example, a xylene isomerization catalyst was prepared in a manner similar to that of Example 3, except that in step (I), an equal mass of hydrogen-type boron-containing ZSM-5 molecular sieve DS2 was used to replace hydrogen-type boron-containing ZSM-5 molecular sieve S3.

[0221] A xylene isomerization catalyst DA2 was obtained.

[0222] In the xylene 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 the alumina is 40 mass%, and the content of the hydrogen-type boron-containing ZSM-5 molecular sieve is 60 mass%.

[0223] Comparative Example 3

[0224] In this comparative example, a xylene isomerization catalyst was prepared according to the method of Example 3, except that in step (I), an equal mass of hydrogen-type boron-containing ZSM-5 molecular sieve DS3 was used to replace hydrogen-type boron-containing ZSM-5 molecular sieve S3.

[0225] A xylene isomerization catalyst DA3 was obtained.

[0226] In the xylene 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 40 mass %, and the content of the ZSM-5 molecular sieve is 60 mass %.

[0227] Comparative Example 4

[0228] In this comparative example, a xylene isomerization catalyst was prepared according to the method of Example 3, except that in step (I), an equal mass of hydrogen-type boron-containing ZSM-5 molecular sieve DS4 was used to replace hydrogen-type boron-containing ZSM-5 molecular sieve S3.

[0229] Xylene isomerization catalyst DA4 was obtained.

[0230] In the xylene 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 40 mass %, and the content of the hydrogen-type boron-containing ZSM-5 molecular sieve is 60 mass %.

[0231] Comparative Example 5

[0232] In this comparative example, a xylene isomerization catalyst was prepared according to the method of Example 3, except that in step (I), 0.35 g of aluminum oxide was used.

[0233] The xylene isomerization catalyst DA5 was obtained.

[0234] In the xylene 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 the alumina is 8 mass%, and the content of the hydrogen-type boron-containing ZSM-5 molecular sieve is 92 mass%.

[0235] Comparative Example 6

[0236] In this comparative example, a xylene isomerization catalyst was prepared according to the method of Example 3, except that in step (I), the platinum content in the chloroplatinic acid used was 0.86 wt%.

[0237] The xylene isomerization catalyst DA6 was obtained.

[0238] In the xylene isomerization catalyst DA6, based on the total dry mass of the composite support, the content of metal platinum is 0.6 mass%; based on the total dry mass of the composite support, the content of the alumina is 40 mass%, and the content of the hydrogen-type boron-containing ZSM-5 molecular sieve is 60 mass%.

[0239] Test Case

[0240] The catalytic performance of the xylene isomerization catalysts prepared in the Examples and Comparative Examples was evaluated, and the isomerization activity and xylene yield were calculated. The specific results are shown in Table 1.

[0241] The evaluation method is as follows: 2 g of the xylene isomerization catalyst listed in Table 1 is loaded into a continuous fixed-bed small-scale hydrogenation unit, and the reaction raw materials are introduced to carry out a xylene isomerization reaction; wherein the raw materials are composed of 10% by mass of ethylbenzene, 55% by mass of m-xylene, and 35% by mass of o-xylene. The reaction conditions are: reaction temperature of 370°C, reaction pressure of 0.8 MPa, hydrogen / hydrocarbon molar ratio of 6, and raw material mass space velocity of 6 h -1 .

[0242] 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.

[0243] The calculation formula of isomerization activity is: (content of p-xylene in the product / total xylene content in the product) × 100%;

[0244] The calculation formula for the xylene yield is: (total xylene content in the product / total xylene content in the raw material)×100%.

[0245] Table 1

[0246] Example No. Isomerization activity, % Xylene yield, % Example 1 23.93 93.2 Example 2 24.04 93.1 Example 3 23.96 95.3 Example 4 23.92 92.5 Example 5 23.78 94.8 Example 6 23.98 89.5 Comparative Example 1 23.67 91.8 Comparative Example 2 23.43 85.8 Comparative Example 3 21.58 96.5 Comparative Example 4 23.48 92.4 Comparative Example 5 23.87 88.6 Comparative Example 6 23.85 81.3

[0247] As can be seen from Table 1, the xylene isomerization catalyst provided by the present invention is used to catalyze the xylene isomerization reaction, which can improve the reaction activity and xylene yield. Among them, the isomerization activity is as high as 24.04%, and the xylene yield is as high as 95.3%.

[0248] 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 ZSM-5 molecular sieve, characterized in that: The molecular sieve contains metal cations; in the hydrogen-type boron-containing ZSM-5 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 0.05-0.7:10-200:1, 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 ZSM-5 molecular sieve according to claim 1, wherein In the hydrogen-type boron-containing ZSM-5 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 0.05-0.5:10-100:

1.

3. The hydrogen-type boron-containing ZSM-5 molecular sieve according to claim 1 or 2, wherein In the hydrogen-type boron-containing ZSM-5 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 ZSM-5 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) performing a first reaction on the first solid material and an ammonium salt solution, and sequentially performing a second drying and a second calcination on the product obtained after the first reaction to obtain a second solid material; (4) performing a second reaction on the second solid material and the metal salt solution, 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 20-1000:0.1-1.5:

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 20-450:0.1-1:

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 0.06-0.5:10-50:0.02-0.2:

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 selected from at least one of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetramethylammonium bromide, tetraethylammonium bromide, tetrapropylammonium bromide and tetrabutylammonium bromide.

13. 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.

14. The method according to claim 4 or 5, wherein: In step (2), the crystallization treatment conditions include at least: a temperature of 120-190° C. and a time of 24-40 hours.

15. 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.

16. 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.

17. The method according to claim 4 or 5, wherein: In step (3), the ammonium salt solution is selected from at least one of ammonium chloride solution and ammonium nitrate solution.

18. 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.

19. 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.

20. The method according to claim 4 or 5, wherein In step (3), the second drying conditions include at least: a temperature of 90-130° C. and a time of 8-20 hours.

21. The method according to claim 4 or 5, wherein In step (3), the second calcination conditions include at least: a temperature of 450-550° C. and a time of 2-6 hours.

22. 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.

23. 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.

24. 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.

25. 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.

26. A xylene isomerization catalyst, characterized in that: The catalyst comprises a composite carrier and metallic platinum supported on the composite carrier, wherein the content of the metallic platinum is 0.02-0.5% by mass based on the total dry mass of the composite carrier; the composite carrier comprises aluminum oxide and the hydrogen-type boron-containing ZSM-5 molecular sieve according to any one of claims 1 to 3, wherein the content of the aluminum oxide is 10-90% by mass and the content of the hydrogen-type boron-containing ZSM-5 molecular sieve is 10-90% by mass based on the total dry mass of the composite carrier.

27. The xylene isomerization catalyst according to claim 26, 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 ZSM-5 molecular sieve is 20-70% by mass.

28. A method for preparing a xylene isomerization catalyst, characterized in that: The method comprises the following steps: (I) contacting and mixing the hydrogen-type boron-containing ZSM-5 molecular sieve according to any one of claims 1 to 3 with alumina (I), and sequentially extruding, drying, and calcining the product obtained after the contacting and mixing (I) to obtain a composite support; (II) contacting and mixing the composite support with a platinum compound solution to impregnate the composite support, and sequentially drying and calcining the impregnated solid material. wherein the amount of the hydrogenated boron-containing ZSM-5 molecular sieve and / or the alumina is controlled so that the content of the alumina in the composite support on a dry basis is 10-90% by mass and the content of the hydrogenated boron-containing ZSM-5 molecular sieve is 10-90% by mass; 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 0.02-0.5% by mass.

29. The method according to claim 28, wherein In step (I), the drying conditions include at least: a temperature of 90-130° C. and a time of 8-20 h.

30. The method of claim 28, 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.

31. The method according to any one of claims 28 to 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.

32. The method according to any one of claims 28 to 30, wherein: In step (II), the conditions of the contact mixing II include at least: a temperature of 10-80° C. and a time of 4-24 h.

33. The method according to any one of claims 28 to 30, wherein: In step (II), the conditions of the contact mixing II include at least: a temperature of 20-50° C. and a time of 5-8 h.

34. The method according to any one of claims 28 to 30, wherein: In step (II), the drying conditions of II include at least: a temperature of 90-130° C. and a time of 8-12 hours.

35. The method according to any one of claims 28 to 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.

36. The method according to any one of claims 28 to 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.

37. The method according to claim 36, 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.

38. The method of claim 36, wherein: In step (II), the reducing gas is hydrogen.

39. A xylene isomerization catalyst prepared by the method according to any one of claims 28 to 38.

40. Use of the xylene isomerization catalyst according to claim 26 or 39 in catalyzing a xylene isomerization reaction.