An EMT molecular sieve, its preparation method, and a catalyst containing the EMT to reduce the bromine index of aromatic hydrocarbons.

Abstract

This invention discloses an EMT molecular sieve, its preparation method, and a catalyst comprising the same for reducing the bromine index of aromatic hydrocarbons. The EMT molecular sieve is a carbon-containing EMT molecular sieve with a carbon content of 0.02–0.5 wt% and a Na₂O content of less than 2.5 wt%. Based on NH₃-TPD results, the ratio of weak acid content to moderately strong acid content of the EMT molecular sieve is (1.05–1.5):1. A catalyst for reducing the bromine index of aromatic hydrocarbons is also disclosed, comprising the EMT molecular sieve, an optional binder, and an optional MWW molecular sieve. A method for reducing the bromine index of aromatic hydrocarbon feedstock is also disclosed, comprising: contacting the aromatic hydrocarbon feedstock with the EMT molecular sieve or the catalyst for reducing the bromine index of aromatic hydrocarbons. The EMT molecular sieve of this invention can be used to reduce the bromine index of aromatic hydrocarbon feedstock by more than 70%.

Description

Technical Field

[0001] This invention belongs to the field of molecular sieves, and particularly relates to an EMT molecular sieve, its preparation method, and a catalyst containing the same to reduce the bromine index of aromatic hydrocarbons. Background Technology

[0002] Molecular sieves possess regular pore structures, good thermal stability, and strong acidity, making them widely used in important catalytic reactions such as hydrocracking, catalytic cracking, and isomerization. Due to the unique structure and excellent catalytic performance of zeolite molecular sieves, their synthesis and application research have attracted significant attention and are becoming increasingly widespread.

[0003] EMT molecular sieves have a zeolite framework structure with a three-dimensional 12-membered ring cross-channel system. They are highly acidic and have a large acid content, making them excellent catalysts for isomerization, aromatization, and alkylation.

[0004] Aromatics are a basic raw material in the petrochemical industry, primarily derived from aromatics complexes. Aromatic products after catalytic reforming all contain a certain amount of olefin impurities. Olefins are highly reactive, easily polymerizing to form gums and potentially reacting with other components to generate non-ideal components, thus significantly impacting the quality of aromatic products.

[0005] On the other hand, some petrochemical processes, such as xylene adsorption separation, are particularly sensitive to olefins. Even if the content of olefin impurities is only a few parts per million, it can have a very adverse effect on the process. In order to obtain qualified chemical raw materials and ensure the smooth progress of subsequent processes, there are refining processes after reforming, aromatic extraction, isomerization, and toluene disproportionation to remove trace amounts of olefin impurities.

[0006] Bleaching clay has acidic centers and, under high pressure liquid phase and 150–200°C conditions, it has certain catalytic superposition and pore adsorption capabilities. It can cause trace amounts of olefins in reformate to undergo hydrocarbonation, polymerization, and other reactions to generate high-boiling-point compounds, which are then adsorbed by the bleaching clay or removed in subsequent separation processes.

[0007] Mining bleaching clay causes permanent environmental damage. Furthermore, deactivated aromatic-containing bleaching clay is extremely harmful to human health and cannot be recycled; it can only be disposed of through landfill, causing serious secondary pollution. With increasing environmental awareness, this issue is receiving growing attention from the government and the public, and manufacturing companies urgently need catalytic deolefins technology to solve these problems.

[0008] Sinopec and CNOOC have developed a molecular sieve-based refining catalyst with USY molecular sieve as the active center. Sinopec's Shanghai Petrochemical Research Institute has successively developed two generations of non-hydrogenated catalytic deolefination catalysts for reformate, DOT-100 and DOT-200. (The last sentence appears to be incomplete and possibly refers to a specific catalyst or process with a weight space velocity of 1.5-1.8 h⁻¹.) -1 Under reaction pressure of 1.1 MPa and reaction temperature of 157-185℃, the single-pass lifetime of DOT-100 is 7-8 times that of bleached clay, and its total lifetime is more than 30 times that of bleached clay. The DOT-200 catalyst, under conditions of an average bromine index of 800 mgBr / 100g feedstock and a weight hourly space velocity of 1.7-1.8 h⁻¹, exhibits similar performance. -1 Under these conditions, the single-cycle lifespan is equivalent to 15 times that of bleached clay, and the total lifespan can reach more than 50 times that of bleached clay. The Tianjin Chemical Research and Design Institute of CNOOC has developed the TCDTO-01 reforming oil catalytic desulfurization system catalyst. It has been reported that the catalyst can be regenerated 3-4 times, with a total lifespan of 1.5-2 years.

[0009] Currently, Y-type molecular sieves are commonly used as catalysts for deolefination. However, due to the small pore diameter of Y-type molecular sieves, the large molecules generated during olefin alkylation cannot escape quickly from their pores, easily leading to pore blockage and deactivation.

[0010] Exxon Mobil developed the Olgone aromatics refining technology, which uses an MCM-22 molecular sieve catalyst instead of clay to remove trace amounts of olefins from reformate without modifying the process. The deactivated catalyst can be reactivated through ex-situ regeneration.

[0011] Exxon Mobil uses MWW molecular sieves and clay as catalysts in CN101309999A to reduce the bromine index of hydrocarbon feedstocks. CN101313052A describes the use of such catalysts for the deolefination reaction of benzene feedstocks containing trace amounts of oxygen compounds.

[0012] Currently, there is no literature on the use of EMT molecular sieve catalysts to reduce the bromine index of aromatic hydrocarbons. Summary of the Invention

[0013] To overcome the problems existing in the prior art, this invention provides an EMT molecular sieve, a method for preparing the same, and a catalyst comprising the same for reducing the bromine index of aromatic hydrocarbons. The EMT molecular sieve is a carbon-containing EMT molecular sieve with a carbon content of 0.02–0.5 wt% and a Na₂O content of less than 2.5 wt%. Based on NH₃-TPD results, the ratio of weak acid content to moderately strong acid content of the EMT molecular sieve is (1.05–1.5):1. A catalyst for reducing the bromine index of aromatic hydrocarbons includes the EMT molecular sieve, an optional binder, and an optional MWW molecular sieve. A method for reducing the bromine index of aromatic hydrocarbon feedstock includes: contacting the aromatic hydrocarbon feedstock with the EMT molecular sieve or the catalyst for reducing the bromine index of aromatic hydrocarbons. The EMT molecular sieve and the catalyst comprising the present invention can be used to reduce the bromine index of aromatic hydrocarbon feedstock by more than 90%.

[0014] One of the objectives of this invention is to provide an EMT molecular sieve, wherein the EMT molecular sieve is a carbon-containing EMT molecular sieve, wherein the carbon content is 0.02 to 0.5 wt%, and the Na2O content in the EMT molecular sieve is less than 2.5 wt%.

[0015] In a preferred embodiment, the EMT molecular sieve is a carbon-containing EMT molecular sieve, wherein the carbon content is 0.02 to 0.2 wt%.

[0016] For example, the carbon content in EMT molecular sieves is 0.02 wt%, 0.05 wt%, 0.08 wt%, 0.1 wt%, 0.12 wt%, 0.15 wt%, 0.18 wt%, or 0.2 wt%.

[0017] In a preferred embodiment, the Na2O content in the EMT molecular sieve is less than 1 wt%.

[0018] In a preferred embodiment, based on the NH3-TPD results, the ratio of the weak acid content to the medium strong acid content of the EMT molecular sieve is (1.05-1.5):1, preferably (1.05-1.3):1.

[0019] For example, the ratio of weak acid content to moderately strong acid content in EMT molecular sieves is 1.05:1, 1.1:1, 1.15:1, 1.2:1, 1.25:1, or 1.3:1. Within these ratio ranges, the catalyst activity remains unaffected, but its stability increases.

[0020] A second objective of this invention is to provide a method for preparing EMT molecular sieves, preferably for preparing the EMT molecular sieve described in one objective of this invention, wherein the preparation method includes:

[0021] (1) Mix aluminum source, sodium hydroxide, silicon source, organic amine and solvent to obtain a mixture;

[0022] (2) The mixture is crystallized, and after crystallization, the solvent is removed, the mixture is washed with water, and dispersed in acid to obtain a dispersion.

[0023] (3) The dispersion is crystallized, and the solvent is removed and the mixture is washed with water after crystallization.

[0024] (4) Drying and calcining to obtain the EMT molecular sieve.

[0025] In this invention, the introduction of organic amines into the feed solution serves two purposes: ① It replaces part of the sodium hydroxide, meaning the amount of sodium hydroxide used in this invention is less than in existing technologies, thus facilitating subsequent sodium exchange; ② The organic amines form residual carbon within the EMT molecular sieve after the subsequent crystallization process. Furthermore, this invention adds organic amines during the in-situ synthesis of the molecular sieve, ensuring uniform distribution of the organic amines within the pores of the molecular sieve.

[0026] In a preferred embodiment, the aluminum source is selected from at least one of aluminum sol, sodium aluminate, aluminum sulfate, aluminum nitrate, and aluminum isopropoxide.

[0027] In a further preferred embodiment, the aluminum source is selected from at least one of aluminum sol and sodium aluminate.

[0028] In a preferred embodiment, the silicon source is selected from at least one of silica sol, water glass, tetraethyl orthosilicate, and sodium silicate.

[0029] In a further preferred embodiment, the silicon source is selected from at least one of silica sol and sodium silicate.

[0030] In a preferred embodiment, the organic amine is a small molecule organic amine.

[0031] In a further preferred embodiment, the organic amine is selected from small molecule organic amines of C1 to C6, preferably from small molecule organic amines of C1 to C4.

[0032] Wherein, the small molecule refers to a molecular weight less than 200, preferably less than 100; for example, the organic amine is selected from at least one of methylamine, ethylamine, propylamine, butylamine, ethylenediamine, propylenediamine, and butyldiamine.

[0033] The reason why this invention preferably uses small molecule organic amines is that high carbon organic amines (such as organic amines with more than C7) are relatively weak in basicity and are not easy to replace sodium hydroxide.

[0034] In a preferred embodiment, the solvent is water.

[0035] In a preferred embodiment, the molar ratio of aluminum source, silicon source, sodium oxide, organic amine, and solvent is 1:(1-20):(2-10):(0.5-20):(100-500), wherein the molar amount of aluminum source is calculated as the molar amount of Al2O3, the molar amount of silicon source is calculated as the molar amount of SiO2, the molar amount of sodium oxide is the total amount including the molar amounts of sodium oxide (Na2O) in the aluminum source and silicon source and the molar amounts of sodium hydroxide converted to sodium oxide (Na2O), and the molar amounts of organic amine and solvent are respectively calculated as the molar amounts of their molecules.

[0036] In a further preferred embodiment, the molar ratio of aluminum source, silicon source, sodium oxide, organic amine and solvent is 1:(3-10):(3-8):(1-10):(150-400), wherein the molar amount of aluminum source is calculated as the molar amount of Al2O3, the molar amount of silicon source is calculated as the molar amount of SiO2, the molar amount of sodium oxide is the total amount including the molar amount of sodium oxide (Na2O) in aluminum source and silicon source and the molar amount of sodium hydroxide converted to sodium oxide (Na2O), and the molar amounts of organic amine and solvent are respectively calculated as the molar amount of their molecules.

[0037] For example, the molar ratio of aluminum source to silicon source is 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9 or 1:10; the molar ratio of aluminum source to sodium oxide is 1:3, 1:4, 1:5, 1:6, 1:7 or 1:8; the molar ratio of aluminum source to organic amine is 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9 or 1:10; and the molar ratio of aluminum source to solvent is 1:150, 1:200, 1:250, 1:300, 1:350 or 1:400.

[0038] In a preferred embodiment, step (1) is performed as follows:

[0039] (1.1) Mix the aluminum source, sodium hydroxide and solvent to obtain solution A;

[0040] (1.2) Mix the silicon source, organic amine, and solvent to obtain solution B;

[0041] (1.3) Cool solutions A and B, then slowly add solution A to solution B to obtain the mixture.

[0042] In a preferred embodiment, the weight concentration of solution A is 3-35 wt%, preferably 4-30 wt%.

[0043] For example, the weight concentration of solution A is 3 wt%, 5 wt%, 10 wt%, 25 wt%, 30 wt%, or 35 wt%.

[0044] In a preferred embodiment, the weight concentration of solution B is 25-50 wt%, preferably 28-48 wt%.

[0045] For example, the weight concentration of solution B is 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, or 50 wt%.

[0046] In a preferred embodiment, in step (1.3), the temperature is cooled to -10 to 10°C, preferably to 0 to 4°C.

[0047] In a preferred embodiment, the crystallization in step (2) is carried out at 5–60°C for 0.5–8 days.

[0048] In a further preferred embodiment, the crystallization in step (2) is carried out at 10–40°C for 1–5 days.

[0049] For example, the crystallization described in step (2) is carried out at 10°C, 20°C, 30°C or 40°C for 1, 2, 3, 4 or 5 days.

[0050] In a preferred embodiment, in step (2), the solvent is removed by vacuum filtration.

[0051] In a preferred embodiment, in step (2), the filtrate is washed with water until the pH of the filtrate is 9-10.

[0052] For example, in step (2), the filtrate is washed with water until the pH of the filtrate is 9, 9.5 or 10.

[0053] In step (2), if the pH is controlled to be below 9, the amount of organic amine will be too low. For example, the organic amine may be washed away by water, resulting in insufficient organic amine in the molecular sieve system.

[0054] In a preferred embodiment, in step (2), the acid is an organic acid.

[0055] In a further preferred embodiment, the organic acid is selected from at least one of formic acid, acetic acid, propionic acid, citric acid, oxalic acid, benzoic acid, and tartaric acid.

[0056] In contrast to the inorganic acids used in existing technologies, this invention uses organic acids because some organic acids will form residual carbon after crystallization and remain inside the molecular sieve.

[0057] In a further preferred embodiment, the pH value of the dispersion is adjusted to 1-5, preferably 2-4, using the acid.

[0058] For example, the pH of the dispersion is adjusted to 2, 2.5, 3, 3.5 or 4 using the acid.

[0059] In a preferred embodiment, in step (3), the crystallization is carried out at 100-300°C for 1-30 hours.

[0060] In a further preferred embodiment, in step (3), the crystallization is carried out at 130–250°C for 4–24 hours.

[0061] For example, in step (3), the crystallization is carried out at 130°C, 150°C, 180°C, 200°C, 230°C or 250°C for 4h, 6h, 10h, 12h, 15h, 18h, 20h, 22h or 24h.

[0062] In a preferred embodiment, in step (3), the solvent is removed by vacuum filtration.

[0063] In a preferred embodiment, in step (3), the filtrate is washed with water until the pH of the filtrate is 6 to 8, for example, pH = 7.

[0064] In a preferred embodiment, in step (4), the drying temperature is 50-150°C, preferably 80-120°C.

[0065] For example, in step (4), the drying temperature is 50°C, 80°C, 100°C, 120°C or 150°C.

[0066] In a preferred embodiment, in step (4), the calcination temperature is 400-650°C, preferably 500-550°C.

[0067] For example, in step (4), the roasting temperature is 400°C, 450°C, 500°C, 550°C, 600°C or 650°C.

[0068] The third objective of this invention is to provide an EMT molecular sieve obtained by the preparation method described in the second objective of this invention.

[0069] The fourth objective of this invention is to provide a catalyst for reducing the bromine index of aromatic hydrocarbons, comprising an EMT molecular sieve, an optional binder, and an optional MWW molecular sieve, wherein the EMT molecular sieve is the EMT molecular sieve described in the first objective of this invention or an EMT molecular sieve obtained by the preparation method described in the second objective of this invention.

[0070] In this invention, "the catalyst comprises an EMT molecular sieve, an optional binder, and an optional MWW molecular sieve" includes the following ranges: "the catalyst comprises an EMT molecular sieve," "the catalyst comprises an EMT molecular sieve and a binder," "the catalyst comprises an EMT molecular sieve and an MWW molecular sieve," or "the catalyst comprises an EMT molecular sieve, a binder, and an MWW molecular sieve." Preferably, the catalyst comprises the EMT molecular sieve and the MWW molecular sieve, as well as an optional binder.

[0071] In a preferred embodiment, the binder is selected from at least one of alumina, silicon dioxide, zirconium oxide, and titanium dioxide.

[0072] In a preferred embodiment, when the catalyst does not contain MWW molecular sieves, the weight content of the EMT molecular sieve is 5-100 wt%, preferably 10-90 wt%; and the weight content of the binder is 0-95 wt%, preferably 10-90 wt%.

[0073] For example, when the catalyst does not contain MWW molecular sieve, the weight content of the EMT molecular sieve is 5wt%, 10wt%, 20wt%, 30wt%, 40wt%, 50wt%, 60wt%, 70wt%, 80wt%, 90wt%, or 100wt%.

[0074] In a preferred embodiment, the MWW molecular sieve is one or more of MCM-22, MCM-36, MCM-49, and MCM-56.

[0075] In a preferred embodiment, when the catalyst contains MWW molecular sieves, the total weight content of the EMT molecular sieves and MWW molecular sieves is 5-100 wt%, preferably 10-90 wt%; the weight content of the binder is 0-95 wt%, preferably 10-90 wt%.

[0076] For example, in the catalyst, the total weight content of the EMT molecular sieve and the MWW molecular sieve is 5 wt%, 10 wt%, 20 wt%, 30 wt%, 40 wt%, 50 wt%, 60 wt%, 70 wt%, 80 wt%, 90 wt%, or 100 wt%.

[0077] In a further preferred embodiment, when the catalyst contains MWW molecular sieve, the weight ratio of EMT molecular sieve to MWW molecular sieve is 5:1 to 1 / 5:1, preferably 3:1 to 1 / 3:1.

[0078] For example, when the catalyst contains MWW molecular sieves, the weight ratio of EMT molecular sieves to MWW molecular sieves is 5:1, 4:1, 3:1, 2:1, 1:1, 4 / 5:1, 3 / 5:1, 2 / 5:1 or 1 / 5:1.

[0079] Among them, EMT and MWW molecular sieves are used as the active components of the catalyst to take into account the adaptability of the catalyst in both low temperature and high temperature ranges (among which EMT performs well in the low temperature range and MWW performs well in the high temperature range).

[0080] The fifth objective of this invention is to provide a method for reducing the bromine index of aromatic feedstock, comprising: contacting and reacting the aromatic feedstock with a catalyst, wherein the catalyst is selected from the EMT molecular sieve described in the first objective of this invention, the EMT molecular sieve obtained by the preparation method described in the second objective of this invention, or the catalyst described in the fourth objective of this invention.

[0081] In a preferred embodiment, the reaction temperature is 150–270°C and the pressure is 0.6 MPa–3.0 MPa.

[0082] In a further preferred embodiment, the reaction temperature is 150–250°C and the pressure is 0.8–2.5 MPa.

[0083] For example, the reaction temperature is 150°C, 180°C, 200°C, 220°C, 250°C, or 270°C; the pressure is 0.6 MPa, 1 MPa, 1.5 MPa, 2 MPa, 2.5 MPa, or 3.0 MPa.

[0084] Using the method described in this invention, the bromine index of the product is reduced by more than 70%, preferably more than 90%, compared with that of the aromatic feedstock.

[0085] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values; these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. In the following, various technical solutions can, in principle, be combined with each other to obtain new technical solutions, which should also be considered as specifically disclosed herein.

[0086] Compared with the prior art, the present invention has the following beneficial effects:

[0087] (1) The EMT molecular sieve used in the catalyst of the present invention has carbon residue and the Na content in the molecular sieve (calculated as Na2O content characterized by XRF) is low.

[0088] (2) The EMT molecular sieve described in this invention can be used to reduce the bromine index of aromatic materials, and the bromine index is reduced by more than 90%. Detailed Implementation

[0089] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0090] It should also be noted that the various specific technical features described in the following embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the various possible combinations will not be described separately in this invention.

[0091] Furthermore, various embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention. The resulting technical solutions are part of the original disclosure of this specification and also fall within the protection scope of the present invention.

[0092] Unless otherwise specified, the raw materials used in the examples and comparative examples are all disclosed in the prior art, such as those that can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0093] [Example 1] Preparation of EMT molecular sieves

[0094] Sodium aluminate and sodium hydroxide were dissolved in distilled water to obtain solution A, with a mass concentration of 11.5 wt%. Silica sol (SiO2 weight percentage 40%), ethylenediamine, and water were mixed and stirred until homogeneous to obtain solution B, with a mass concentration of 29.1 wt%. Solutions A and B were cooled separately in an ice bath at 4°C. Then, solution A was slowly added to solution B under magnetic stirring to form a mixture. The molar ratio of the mixture was controlled at Al2O3:SiO2:Na2O:ethylenediamine:H2O = 1:5.3:3.7:3.3:180. The mixture was crystallized at 30°C for 3 days to obtain a suspension. This suspension was filtered under reduced pressure and washed with distilled water until the pH reached 10. The filter cake was dispersed in water, and oxalic acid was added to adjust the pH to 3. The dispersion was crystallized at 230℃ for 12 hours. After crystallization, it was filtered under reduced pressure and washed with distilled water until the pH reached 7. The filter cake was dried at 120℃ and calcined at 550℃ for 3 hours to obtain a carbon-containing EMT molecular sieve (named EMT-1). The Si / Al ratio was 1.5, the carbon content was 0.10 wt%, and the Na2O content was 0.83 wt%. Based on the NH3-TPD results, the ratio of weak acid content to medium-strong acid content in the carbon-containing EMT molecular sieve catalyst was 1.08:1.

[0095] [Example 2] Preparation of EMT molecular sieves

[0096] Aluminum sulfate and sodium hydroxide were dissolved in distilled water to obtain solution A, with a mass concentration of 24.8 wt%. Sodium silicate, propylenediamine, and water were mixed and stirred until homogeneous to obtain solution B, with a mass concentration of 45.9 wt%. Solutions A and B were cooled separately in an ice bath at 4°C. Then, solution A was slowly added to solution B under magnetic stirring to form a mixture. The molar ratio of the mixture was controlled to be Al₂O₃:SiO₂:Na₂O:propylenediamine:H₂O = 1:5.0:6.9:3.7:240. The mixture was crystallized at 30°C for 3 days to obtain a suspension. The suspension was filtered under reduced pressure and washed with distilled water until the pH reached 9.5. The filter cake was dispersed in water, and citric acid was added to adjust the pH to 4. The dispersion was crystallized at 200℃ for 24 hours. After crystallization, it was filtered under reduced pressure and washed with distilled water until the pH reached 7. The filter cake was dried at 120℃ and calcined at 550℃ for 3 hours to obtain a carbon-containing EMT molecular sieve (named EMT-2). The Si / Al ratio was 1.2, the carbon content was 0.07wt%, and the Na2O content was 0.95wt%. Based on the NH3-TPD results, the ratio of weak acid content to medium-strong acid content in the carbon-containing EMT molecular sieve catalyst was 1.05:1.

[0097] [Example 3] Preparation of EMT molecular sieves

[0098] Sodium aluminate and sodium hydroxide were dissolved in distilled water to obtain solution A, with a mass concentration of 10.7 wt%. Sodium silicate, ethylenediamine, and water were mixed and stirred until homogeneous to obtain solution B, with a mass concentration of 34.1 wt%. Solutions A and B were cooled separately in an ice bath at 4°C. Then, solution A was slowly added to solution B under magnetic stirring to form a mixture. The molar ratio of the mixture was controlled to be Al₂O₃:SiO₂:Na₂O:ethylenediamine:H₂O = 1:5.2:7.2:4.8:300. The mixture was crystallized at 30°C for 3 days to obtain a suspension. The suspension was filtered under reduced pressure and washed with distilled water until the pH reached 10. The filter cake was dispersed in water, and oxalic acid was added to adjust the pH to 2. The dispersion was crystallized at 230℃ for 24 hours. After crystallization, it was filtered under reduced pressure and washed with distilled water until the pH reached 7. The filter cake was dried at 120℃ and calcined at 550℃ for 3 hours to obtain a carbon-containing EMT molecular sieve (named EMT-3). The Si / Al ratio was 1.3, the carbon content was 0.16 wt%, and the Na2O content was 0.79 wt%. Based on the NH3-TPD results, the ratio of weak acid content to medium-strong acid content in the carbon-containing EMT molecular sieve catalyst was 1.22:1.

[0099] [Example 4] Preparation of EMT molecular sieves

[0100] Aluminum sol (Al₂O₃ weight percentage 24%) and sodium hydroxide were dissolved in distilled water to obtain solution A, with a mass concentration of 4.1 wt%. Sodium silicate, butanediamine, and water were mixed and stirred until homogeneous to obtain solution B, with a mass concentration of 42.8 wt%. Solutions A and B were cooled separately in an ice bath at 4°C. Then, solution A was slowly added to solution B under magnetic stirring to form a mixture. The molar ratio of the mixture was controlled to be Al₂O₃:SiO₂:Na₂O:butanediamine:H₂O = 1:5.1:6.6:5:270. The mixture was crystallized at 30°C for 3 days to obtain a suspension. The suspension was filtered under reduced pressure and washed with distilled water until the pH reached 9. The filter cake was dispersed in water, and acetic acid was added to adjust the pH to 3. The dispersion was crystallized at 250℃ for 12 hours. After crystallization, it was filtered under reduced pressure and washed with distilled water until the pH reached 7. The filter cake was dried at 120℃ and calcined at 550℃ for 3 hours to obtain a carbon-containing EMT molecular sieve (named EMT-4). The Si / Al ratio was 1.7, the carbon content was 0.12 wt%, and the Na2O content was 0.74 wt%. Based on the NH3-TPD results, the ratio of weak acid content to medium-strong acid content in the carbon-containing EMT molecular sieve catalyst was 1.15:1.

[0101] [Example 5] Preparation of EMT molecular sieves

[0102] Sodium aluminate and sodium hydroxide were dissolved in distilled water to obtain solution A, with a mass concentration of 10.7 wt%. Sodium silicate, an aqueous solution of ethylamine (ethylamine content 65-70%), and water were mixed and stirred until homogeneous to obtain solution B, with a mass concentration of 34.8 wt%. Solutions A and B were cooled separately in an ice bath at 4°C. Then, under magnetic stirring, solution A was slowly added to solution B to form a mixture. The molar ratio of the mixture was controlled to be Al₂O₃:SiO₂:Na₂O:ethylamine:H₂O = 1:5.2:7.2:10:300. The mixture was crystallized at 30°C for 3 days to obtain a suspension. The suspension was filtered under reduced pressure and washed with distilled water until the pH reached 10. The filter cake was dispersed in water, and oxalic acid was added to adjust the pH to 2. The dispersion was crystallized at 230℃ for 24 hours. After crystallization, it was filtered under reduced pressure and washed with distilled water until the pH reached 7. The filter cake was dried at 120℃ and calcined at 550℃ for 3 hours to obtain a carbon-containing EMT molecular sieve (named EMT-5). The Si / Al ratio was 1.8, the carbon content was 0.19 wt%, and the Na2O content was 0.66 wt%. Based on the NH3-TPD results, the ratio of weak acid content to medium-strong acid content in the carbon-containing EMT molecular sieve catalyst was 1.11:1.

[0103] [Example 6] Method for reducing the bromine index of aromatic feedstock

[0104] EMT-1 and alumina were molded and calcined according to a formula of 80% and 20% by weight (dry basis) to obtain catalyst EM-1 for reducing the bromine index of aromatic feedstock.

[0105] Five g of the above catalyst was used in a fixed-bed reactor for a non-hydrogenated deolefins test on reformed oil. The feedstock was mixed xylene from the bottom of a reformer deheptane removal tower, with a bromine index of 1000 mgBr / 100 g oil. The reaction pressure was 2.0 MPa and the space velocity was 25.0 h⁻¹. -1 Using an export bromine index of 200 mgBr / 100g oil as the standard, the reaction times at temperatures of 150℃, 170℃, 190℃, 210℃, 230℃ and 250℃ were 80 hours, 70 hours, 55 hours, 20 hours, 5 hours and 0 hours, respectively.

[0106] [Example 7] Method for reducing the bromine index of aromatic feedstock

[0107] EMT-2 and alumina were shaped and calcined according to a formula of 80% and 20% by weight (dry basis) to obtain catalyst EM-2 for reducing the bromine index of aromatic feedstock.

[0108] Five g of the above catalyst was used in a fixed-bed reactor for a non-hydrogenated deolefins test on reformed oil. The feedstock was mixed xylene from the bottom of a reformer deheptane removal tower, with a bromine index of 1000 mgBr / 100 g oil. The reaction pressure was 2.0 MPa and the space velocity was 25.0 h⁻¹. -1 Using an export bromine index of 200 mgBr / 100g oil as the standard, the reaction times at temperatures of 150℃, 170℃, 190℃, 210℃, 230℃ and 250℃ were 70 hours, 55 hours, 50 hours, 30 hours, 0 hours and 0 hours, respectively.

[0109] [Example 8] Method for reducing the bromine index of aromatic feedstock

[0110] EMT-3 and alumina were molded and calcined according to a formula of 80% and 20% by weight (dry basis) to obtain EM-3, a catalyst for reducing the bromine index of aromatic feedstocks.

[0111] Five g of the above catalyst was used in a fixed-bed reactor for a non-hydrogenated deolefins test on reformed oil. The feedstock was mixed xylene from the bottom of a reformer deheptane removal tower, with a bromine index of 1000 mgBr / 100 g oil. The reaction pressure was 2.0 MPa and the space velocity was 25.0 h⁻¹. -1 Using an export bromine index of 200 mgBr / 100g oil as the standard, the reaction times at temperatures of 150℃, 170℃, 190℃, 210℃, 230℃ and 250℃ were 95 hours, 80 hours, 65 hours, 20 hours, 5 hours and 0 hours, respectively.

[0112] [Example 9] Method for reducing the bromine index of aromatic feedstock

[0113] EMT-5 and alumina were molded and calcined according to a formula of 80% and 20% by weight (dry basis) to obtain catalyst EM-4 for reducing the bromine index of aromatic feedstock.

[0114] Five g of the above catalyst was used in a fixed-bed reactor for a non-hydrogenated deolefins test on reformed oil. The feedstock was mixed xylene from the bottom of a reformer deheptane removal tower, with a bromine index of 1000 mgBr / 100 g oil. The reaction pressure was 2.0 MPa and the space velocity was 25.0 h⁻¹. -1 Using an export bromine index of 200 mgBr / 100g oil as the standard, the reaction times at temperatures of 150℃, 170℃, 190℃, 210℃, 230℃ and 250℃ were 65 hours, 60 hours, 40 hours, 25 hours, 0 hours and 0 hours, respectively.

[0115] As can be seen from the results of Examples 6 to 9, the EMT molecular sieve can maintain high initial activity and stability in the range of 150 to 210°C (especially 150 to 190°C).

[0116] [Example 10] Method for reducing the bromine index of aromatic feedstock

[0117] Na-MCM-22 with Si / Al2=30 was exchanged to obtain NH4-MCM-22. NH4-MCM-22, EMT-1, and alumina were shaped and calcined according to formulations of 30%, 50%, and 20% (by weight, dry basis) to obtain catalyst EM-5 for reducing the bromine index of aromatic feedstocks.

[0118] Five g of the above catalyst was used in a fixed-bed reactor for a non-hydrogenated deolefins test on reformed oil. The feedstock was mixed xylene from the bottom of a reformer deheptane removal tower, with a bromine index of 1000 mgBr / 100 g oil. The reaction pressure was 2.0 MPa and the space velocity was 25.0 h⁻¹. -1 Using an export bromine index of 200 mgBr / 100g oil as the standard, the reaction times at temperatures of 150℃, 170℃, 190℃, 210℃, 230℃ and 250℃ were 50 hours, 45 hours, 60 hours, 50 hours, 40 hours and 40 hours, respectively.

[0119] [Example 11] Method for reducing the bromine index of aromatic feedstock

[0120] Na-MCM-22 with Si / Al2=30 was exchanged to obtain NH4-MCM-22. NH4-MCM-22, EMT-2, and alumina were shaped and calcined according to formulations of 30%, 50%, and 20% (by weight, dry basis) to obtain catalyst EM-6 for reducing the bromine index of aromatic feedstocks.

[0121] Five g of the above catalyst was used in a fixed-bed reactor for a non-hydrogenated deolefins test on reformed oil. The feedstock was mixed xylene from the bottom of a reformer deheptane removal tower, with a bromine index of 1000 mgBr / 100 g oil. The reaction pressure was 2.0 MPa and the space velocity was 25.0 h⁻¹. -1Using an export bromine index of 200 mgBr / 100g oil as the standard, the reaction times at temperatures of 150℃, 170℃, 190℃, 210℃, 230℃ and 250℃ were 45 hours, 45 hours, 65 hours, 60 hours, 40 hours and 40 hours, respectively.

[0122] [Example 12] Method for reducing the bromine index of aromatic feedstock

[0123] Na-MCM-22 with Si / Al2 = 30 was exchanged to obtain NH4-MCM-22. NH4-MCM-22, EMT-3, and alumina were shaped and calcined according to formulations of 30%, 50%, and 20% (by weight, dry basis) to obtain catalyst EM-7 for reducing the bromine index of aromatic feedstocks.

[0124] Five g of the above catalyst was used in a fixed-bed reactor for a non-hydrogenated deolefins test on reformed oil. The feedstock was mixed xylene from the bottom of a reformer deheptane removal tower, with a bromine index of 1000 mgBr / 100 g oil. The reaction pressure was 2.0 MPa and the space velocity was 25.0 h⁻¹. -1 Using an export bromine index of 200 mgBr / 100g oil as the standard, the reaction times at temperatures of 150℃, 170℃, 190℃, 210℃, 230℃ and 250℃ were 70 hours, 55 hours, 75 hours, 70 hours, 40 hours and 40 hours, respectively.

[0125] The results of Examples 10-12 show that the combined catalyst of EMT molecular sieve and MWW molecular sieve can maintain its activity for a long time in a wide temperature range of 150-250°C; indicating that the combined catalyst of EMT molecular sieve and MWW molecular sieve can operate not only at low temperature conditions but also at high temperature conditions.

[0126] Comparative Example 1

[0127] The process of Example 1 was repeated, except that in the preparation of EMT molecular sieves, organic amines were not used, and only sodium hydroxide was used to adjust the alkalinity.

[0128] Sodium aluminate and sodium hydroxide were dissolved in distilled water to obtain solution A. Silica sol (40% SiO2 by weight), sodium hydroxide, and water were mixed and stirred until homogeneous to obtain solution B. Solutions A and B were cooled separately in an ice bath at 4°C. Then, solution A was slowly added to solution B under magnetic stirring to form a mixture. The molar ratio of the mixture was controlled at Al₂O₃:SiO₂:Na₂O:H₂O = 1:5.3:17.8:180. The mixture was crystallized at 30°C for 3 days to obtain a suspension. This suspension was filtered under reduced pressure and washed with distilled water until the pH reached 10. The filter cake was dispersed in water, and oxalic acid was added to adjust the pH to 3. The dispersion was crystallized at 230℃ for 12 hours. After crystallization, it was filtered under reduced pressure and washed with distilled water until the pH reached 7. The filter cake was dried at 120℃ and calcined at 550℃ for 3 hours to obtain a carbon-containing EMT molecular sieve (named EMT-6). The Si / Al ratio was 1.2, the carbon content was 0.04 wt%, and the Na2O content was 6.55 wt%. Based on the NH3-TPD results, the ratio of weak acid content to medium-strong acid content in the carbon-containing EMT molecular sieve catalyst was 0.84:1.

[0129] Comparative Example 2

[0130] Repeat the process of Example 1, except that the C1-C4 organic amines are replaced with an equal amount of octanediamine.

[0131] Sodium aluminate and sodium hydroxide were dissolved in distilled water to obtain solution A; silica sol (SiO2 weight percentage 40%), octanediamine, and water were mixed and stirred until homogeneous to obtain solution B; solutions A and B were cooled separately in an ice bath at 4°C, and then A was slowly added to B under magnetic stirring to form a mixture. The molar ratio of the mixture was controlled at Al2O3:SiO2:Na2O:octanediamine:H2O = 1:5.3:3.7:3.3:180. The mixture was crystallized at 30°C for 3 days to obtain a suspension, which was then filtered under reduced pressure and washed with distilled water until the pH reached 10. XRD characterization of the dried sample showed that the product was amorphous and lacked the characteristic diffraction peaks of EMT molecular sieves.

[0132] Comparative Example 3

[0133] Repeat the process of Example 1, except that the pH is adjusted to 8 in step (2).

[0134] Sodium aluminate and sodium hydroxide were dissolved in distilled water to obtain solution A. Silica sol (SiO2 weight percentage 40%), ethylenediamine, and water were mixed and stirred until homogeneous to obtain solution B. Solutions A and B were cooled separately in an ice bath at 4°C. Then, solution A was slowly added to solution B under magnetic stirring to form a mixture. The molar ratio of the mixture was controlled to be Al2O3:SiO2:Na2O:ethylenediamine:H2O = 1:5.3:3.7:3.3:180. The mixture was crystallized at 30°C for 3 days to obtain a suspension. This suspension was filtered under reduced pressure and washed with distilled water until the pH reached 8. The filter cake was dispersed in water, and oxalic acid was added to adjust the pH to 3. The dispersion was crystallized at 230℃ for 12 hours. After crystallization, it was filtered under reduced pressure and washed with distilled water until the pH reached 7. The filter cake was dried at 120℃ and calcined at 550℃ for 3 hours to obtain a carbon-containing EMT molecular sieve (named EMT-7). The Si / Al ratio was 1.5, the carbon content was 0.01 wt%, and the Na2O content was 0.80 wt%. Based on the NH3-TPD results, the ratio of weak acid content to medium-strong acid content in the carbon-containing EMT molecular sieve catalyst was 1.02:1.

[0135] Comparative Example 4

[0136] Repeat the process of Example 1, except that an equal amount of hydrochloric acid is used to replace the organic acid.

[0137] Sodium aluminate and sodium hydroxide were dissolved in distilled water to obtain solution A. Silica sol (SiO2 weight percentage 40%), ethylenediamine, and water were mixed and stirred until homogeneous to obtain solution B. Solutions A and B were cooled separately in an ice bath at 4°C. Then, solution A was slowly added to solution B under magnetic stirring to form a mixture. The molar ratio of the mixture was controlled to be Al2O3:SiO2:Na2O:ethylenediamine:H2O = 1:5.3:3.7:3.3:180. The mixture was crystallized at 30°C for 3 days to obtain a suspension. This suspension was filtered under reduced pressure and washed with distilled water until the pH reached 10. The filter cake was dispersed in water, and hydrochloric acid was added to adjust the pH to 3. The dispersion was crystallized at 230℃ for 12 hours. After crystallization, it was filtered under reduced pressure and washed with distilled water until the pH reached 7. The filter cake was dried at 120℃ and calcined at 550℃ for 3 hours to obtain a carbon-containing EMT molecular sieve (named EMT-8). The Si / Al ratio was 1.3, the carbon content was 0.03 wt%, and the Na2O content was 3.17 wt%. Based on the NH3-TPD results, the ratio of weak acid content to medium-strong acid content in the carbon-containing EMT molecular sieve catalyst was 0.83:1.

[0138] Comparative Example 5

[0139] The method for reducing the bromine index of aromatic feedstock in Example 6 was repeated, except that EMT-6 prepared in Comparative Example 1 was used instead of EMT-1 prepared in Example 1.

[0140] EMT-6 and alumina were shaped and calcined according to a formula of 80% and 20% by weight (dry basis) to obtain catalyst EM-8.

[0141] Five g of the above catalyst was used in a fixed-bed reactor for a non-hydrogenated deolefins test on reformed oil. The feedstock was mixed xylene from the bottom of a reformer deheptane removal tower, with a bromine index of 1000 mgBr / 100 g oil. The reaction pressure was 2.0 MPa and the space velocity was 25.0 h⁻¹. -1 Using an export bromine index of 200 mgBr / 100g oil as the standard, the reaction times at temperatures of 150℃, 170℃, 190℃, 210℃, 230℃ and 250℃ were 10 hours, 15 hours, 10 hours, 0 hours, 0 hours and 0 hours, respectively.

[0142] Comparative Example 6

[0143] The method for reducing the bromine index of aromatic feedstock in Example 6 was repeated, except that the EMT prepared in Comparative Example 2 was used instead of the EMT prepared in Example 1.

[0144] Catalyst EM-9 was obtained by molding and calcining the amorphous material prepared in Comparative Example 2 with alumina according to a formula of 80% and 20% by weight (dry basis).

[0145] Five g of the above catalyst was used in a fixed-bed reactor for a non-hydrogenated deolefins test on reformed oil. The feedstock was mixed xylene from the bottom of a reformer deheptane removal tower, with a bromine index of 1000 mgBr / 100 g oil. The reaction pressure was 2.0 MPa and the space velocity was 25.0 h⁻¹. -1 Based on an export bromine index of 200 mgBr / 100g oil as the standard, it showed no deolefination activity under conditions of 150–250℃.

[0146] Comparative Example 7

[0147] The method for reducing the bromine index of aromatic feedstock in Example 6 was repeated, except that EMT-7 prepared in Comparative Example 3 was used instead of EMT-1 prepared in Example 1.

[0148] EMT-7 and alumina were shaped and calcined according to a formula of 80% and 20% by weight (dry basis) to obtain catalyst EM-10.

[0149] Five g of the above catalyst was used in a fixed-bed reactor for a non-hydrogenated deolefins test on reformed oil. The feedstock was mixed xylene from the bottom of a reformer deheptane removal tower, with a bromine index of 1000 mgBr / 100 g oil. The reaction pressure was 2.0 MPa and the space velocity was 25.0 h⁻¹. -1 Using an export bromine index of 200 mgBr / 100g oil as the standard, the reaction times at temperatures of 150℃, 170℃, 190℃, 210℃, 230℃ and 250℃ were 70 hours, 40 hours, 15 hours, 5 hours, 0 hours and 0 hours, respectively.

[0150] Comparative Example 8

[0151] The method for reducing the bromine index of aromatic feedstock in Example 6 was repeated, except that EMT-8 prepared in Comparative Example 4 was used instead of EMT-1 prepared in Example 1.

[0152] EMT-8 and alumina were shaped and calcined according to a formula of 80% and 20% by weight (dry basis) to obtain catalyst EM-11.

[0153] Five g of the above catalyst was used in a fixed-bed reactor for a non-hydrogenated deolefins test on reformed oil. The feedstock was mixed xylene from the bottom of a reformer deheptane removal tower, with a bromine index of 1000 mgBr / 100 g oil. The reaction pressure was 2.0 MPa and the space velocity was 25.0 h⁻¹. -1 Using an export bromine index of 200 mgBr / 100g oil as the standard, the reaction times at temperatures of 150℃, 170℃, 190℃, 210℃, 230℃ and 250℃ were 30 hours, 35 hours, 10 hours, 0 hours, 0 hours and 0 hours, respectively.

[0154] Comparative Example 9

[0155] The inventors conducted experiments similar to those of Comparative Examples 6-8, except that they replaced the EMT molecular sieve in Example 8 with the EMT molecular sieves of Comparative Examples 1-4 respectively. They found that the experimental results were also worse than those of Example 8.

[0156] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. An EMT molecular sieve, wherein the EMT molecular sieve is a carbon-containing EMT molecular sieve, wherein the carbon content is 0.02-0.5 wt%, and the Na2O content in the EMT molecular sieve is less than 2.5 wt%; and the ratio of the weak acid content to the medium strong acid content of the EMT molecular sieve, based on NH3-TPD results, is (1.05-1.5):

1.

2. The EMT molecular sieve according to claim 1, characterized in that, The EMT molecular sieve is a carbon-containing EMT molecular sieve, wherein the carbon content is 0.02–0.2 wt%; and / or, The Na₂O content in the EMT molecular sieve is less than 1 wt%.

3. The EMT molecular sieve according to claim 1 or 2, characterized in that, Based on the NH3-TPD results, the ratio of weak acid content to medium strong acid content of EMT molecular sieve is (1.05-1.3):

1.

4. A method for preparing an EMT molecular sieve, used to prepare the EMT molecular sieve according to any one of claims 1 to 3, the preparation method comprising: (1) An aluminum source, sodium hydroxide, silicon source, organic amine, and solvent are mixed to obtain a mixture; the organic amine is selected from small molecule organic amines of C1 to C6. (2) The mixture is crystallized. After crystallization, the solvent is removed, the mixture is washed with water, and dispersed in acid to obtain a dispersion. In step (2), the mixture is washed with water until the pH of the filtrate is 9-10. The acid is an organic acid. (3) The dispersion is crystallized, and the solvent is removed and the mixture is washed with water after crystallization. (4) Drying and calcining to obtain the EMT molecular sieve.

5. The preparation method according to claim 4, characterized in that, The aluminum source is selected from at least one of aluminum sol, sodium aluminate, aluminum sulfate, aluminum nitrate, and aluminum isopropoxide; and / or, The silicon source is selected from at least one of silica sol, water glass, tetraethyl orthosilicate, and sodium silicate; and / or, The organic amine is selected from small molecule organic amines of C1 to C4.

6. The preparation method according to claim 4, characterized in that, The aluminum source is selected from at least one of aluminum sol and sodium aluminate; and / or, The silicon source is selected from at least one of silica sol and sodium silicate; and / or, The organic amine is selected from at least one of methylamine, ethylamine, propylamine, butylamine, ethylenediamine, propylenediamine, and butylenediamine.

7. The preparation method according to claim 4, characterized in that, The molar ratio of aluminum source, silicon source, sodium oxide, organic amine and solvent is 1:(1~20):(2~10):(0.5~20):(100~500); wherein, the molar amount of aluminum source is calculated as the molar amount of Al2O3, the molar amount of silicon source is calculated as the molar amount of SiO2, the molar amount of sodium oxide is the total amount including the molar amount of sodium oxide in aluminum source and silicon source and the molar amount of sodium hydroxide converted to sodium oxide, and the molar amounts of organic amine and solvent are calculated as the molar amount of their molecules.

8. The preparation method according to claim 4, characterized in that, The molar ratio of aluminum source, silicon source, sodium oxide, organic amine and solvent is 1:(3~10):(3~8):(1~10):(150~400); wherein, the molar amount of aluminum source is calculated as the molar amount of Al2O3, the molar amount of silicon source is calculated as the molar amount of SiO2, the molar amount of sodium oxide is the total amount including the molar amount of sodium oxide in aluminum source and silicon source and the molar amount of sodium hydroxide converted to sodium oxide, and the molar amounts of organic amine and solvent are calculated as the molar amount of their molecules.

9. The preparation method according to claim 4, characterized in that, Step (1) is performed as follows: (1.1) Mix the aluminum source, sodium hydroxide and solvent to obtain solution A; (1.2) Mix the silicon source, organic amine, and solvent to obtain solution B; (1.3) Cool solutions A and B, then add solution A to solution B to obtain the mixture.

10. The preparation method according to claim 9, characterized in that, The weight concentration of solution A is 3–35 wt%; and / or, The weight concentration of solution B is 25–50 wt%; and / or, In step (1.3), the temperature is cooled to -10 to 10°C.

11. The preparation method according to claim 4, characterized in that, The crystallization described in step (2) is carried out at 5–60°C for 0.5–8 days; and / or, In step (2), the solvent is removed by vacuum filtration; and / or, In step (2), the organic acid is selected from at least one of formic acid, acetic acid, propionic acid, citric acid, oxalic acid, benzoic acid, and tartaric acid.

12. The preparation method according to claim 4, characterized in that, In step (3), the crystallization is carried out at 100–300°C for 1–30 hours; and / or, In step (3), the solvent is removed by vacuum filtration; and / or, In step (3), the filtrate is washed with water until the pH of the filtrate reaches 6-8.

13. The preparation method according to any one of claims 4 to 12, characterized in that, In step (4), the drying temperature is 50–150°C; and / or, In step (4), the roasting temperature is 400-650°C.

14. EMT molecular sieves obtained by the preparation method according to any one of claims 4 to 13.

15. A catalyst for reducing the bromine index of aromatic hydrocarbons, comprising an EMT molecular sieve, an optional binder, and an optional MWW molecular sieve, wherein, The EMT molecular sieve is the EMT molecular sieve described in any one of claims 1 to 3 or the EMT molecular sieve obtained by the preparation method described in any one of claims 4 to 13.

16. The catalyst according to claim 15, characterized in that, The binder is selected from at least one of alumina, silicon dioxide, zirconium oxide, and titanium dioxide; and / or, The MWW molecular sieve is one or more of MCM-22, MCM-36, MCM-49 and MCM-56.

17. The catalyst according to claim 15 or 16, characterized in that, When the catalyst does not contain MWW molecular sieve, the weight content of EMT molecular sieve is 5-100 wt%.

18. The catalyst according to claim 15 or 16, characterized in that, When the catalyst does not contain MWW molecular sieve, the weight content of EMT molecular sieve is 10-90 wt%.

19. The catalyst according to claim 15 or 16, characterized in that, When the catalyst contains MWW molecular sieves, the total weight content of the EMT molecular sieves and MWW molecular sieves is 5-100 wt%; and / or When the catalyst contains MWW molecular sieve, the weight ratio of EMT molecular sieve to MWW molecular sieve is 5:1 to 1 / 5:

1.

20. The catalyst according to claim 15 or 16, characterized in that, When the catalyst contains MWW molecular sieves, the total weight content of the EMT molecular sieves and MWW molecular sieves is 10–90 wt%; and / or When the catalyst contains MWW molecular sieve, the weight ratio of EMT molecular sieve to MWW molecular sieve is 3:1 to 1 / 3:

1.

21. A method for reducing the bromine index of aromatic feedstock, comprising: The aromatic feedstock reacts with a catalyst, wherein the catalyst is selected from the EMT molecular sieve of any one of claims 1 to 3, the EMT molecular sieve obtained by the preparation method of any one of claims 4 to 13, or the catalyst of any one of claims 15 to 20.

22. The method according to claim 21, characterized in that, The reaction is carried out at a temperature of 150–270°C and a pressure of 0.6 MPa–3.0 MPa.