Modified emt molecular sieve, method for preparing same, and use thereof

Abstract

This invention discloses a modified EMT molecular sieve, its preparation method, and its applications. The modified EMT molecular sieve comprises an EMT molecular sieve matrix and a silicon crystalline phase layer located on the surface of the EMT molecular sieve matrix. By modifying the surface of the EMT molecular sieve with a silicon crystalline phase layer, this invention effectively reduces the dealumination phenomenon of the EMT molecular sieve under high-temperature and water-containing conditions, maximizing the preservation of its active sites. The modified EMT molecular sieve can be used to treat water-containing materials at high temperatures, such as for the de-olefinization treatment of aromatic materials or for reducing the bromine index of aromatic materials.

Description

Technical Field

[0001] This invention belongs to the field of molecular sieves, and particularly relates to EMT molecular sieves. Specifically, it relates to a modified EMT molecular sieve, its preparation method, and its application. 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] CN107814393A discloses a method for rapid crystallization synthesis of EMT molecular sieves. The method involves adding EMT molecular sieve seed crystals synthesized under template-free conditions to the synthesis system and forming a gel. After aging the gel, it undergoes hydrothermal crystallization for 12–72 hours, followed by microwave crystallization for 4–360 minutes to synthesize the EMT molecular sieve. Compared with existing technologies, this invention's method for synthesizing EMT molecular sieves uses less template agent, has a shorter molecular sieve crystallization time, higher crystallinity, and lower energy consumption.

[0005] CN110893337A discloses a method for preparing EMT molecular sieves and their application in the adsorption of volatile organic gases. First, polyethylene glycol is completely dissolved in deionized water. After complete dissolution with sodium hydroxide, an aluminum source is added and stirred thoroughly to form solution A. Solution B is prepared by completely dissolving a silicon source in another portion of sodium hydroxide solution, and stirring thoroughly until a clear solution is obtained. Solutions A and B are placed in an ice-water mixture. Then, solution B is added dropwise to solution A, and stirring is continued until a homogeneous gel mixture is formed. The resulting homogeneous gel mixture is transferred to a high-pressure reactor and crystallized at a certain temperature for a period of time. After crystallization, it is cooled to room temperature, and the solid product is washed with deionized water, dried, and calcined to obtain the EMT molecular sieve. The polyethylene glycol used in the synthesized EMT molecular sieve is inexpensive, reducing production costs. Furthermore, the synthesized molecular sieve exhibits good crystallinity, high solid-phase yield, and excellent adsorption performance, which is of great significance for the industrial promotion and application of EMT molecular sieves.

[0006] Existing technologies for EMT molecular sieves largely focus on reducing the amount of expensive template agents used or finding alternatives, with limited research on the modification of EMT molecular sieves. In particular, no existing technology addresses the development of modified EMT molecular sieves that can effectively treat aqueous materials at high temperatures with excellent performance; for example, modified EMT molecular sieves capable of deolefinizing aqueous aromatic materials. Summary of the Invention

[0007] To overcome the problems existing in the prior art, the present invention provides a modified EMT molecular sieve, its preparation method and application. The modified EMT molecular sieve can be used to treat water-containing materials at high temperatures, such as to perform deolefination treatment on aromatic materials or to reduce the bromine index of aromatic materials.

[0008] One of the objectives of this invention is to provide a modified EMT molecular sieve, which includes an EMT molecular sieve matrix and a silicon crystal phase layer located on the surface of the EMT molecular sieve matrix.

[0009] In a preferred embodiment, the silicon crystal phase layer accounts for 2 to 20 wt% of 100 wt% of the modified EMT molecular sieve, for example, 2 wt%, 5 wt%, 8 wt%, 10 wt%, 12 wt%, 15 wt%, 18 wt%, or 20 wt%.

[0010] In a further preferred embodiment, with the modified EMT molecular sieve comprising 100 wt%, the silicon crystal phase layer comprises 3 to 10 wt%, for example, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, or 10 wt%.

[0011] EMT molecular sieves have a low silica-to-alumina ratio and a high aluminum content, making them prone to dealuminization during high-temperature treatment of aqueous materials. This leads to a significant reduction in the number of active sites, directly impacting the catalyst's treatment efficiency. To address this issue, the inventors, after extensive experimental research, discovered that modifying the surface of the EMT molecular sieve with a silicon crystalline phase layer effectively reduces dealuminization under high-temperature, aqueous conditions, maximizing the preservation of active sites. The reason for this is likely that the hydrophobic nature of the surface silicon significantly reduces water ingress into the molecular sieve, thereby minimizing dealuminization within the matrix. Since the material to be treated is organic, it can enter the molecular sieve matrix through the pores of the surface silicon crystalline phase layer, facilitating its treatment.

[0012] In a preferred embodiment, the silicon crystal phase layer has a coverage of more than 85% on the surface of the EMT molecular sieve matrix.

[0013] The estimation method for the surface silicon crystal phase layer coverage is as follows: XPS is used to determine the silicon-to-aluminum ratio of the EMT matrix, the surface silicon crystal phase layer is based on pure silicon, and the silicon-to-aluminum ratio of the modified EMT molecular sieve is then determined. The surface silicon crystal phase layer coverage is calculated based on the difference between the two silicon-to-aluminum ratios.

[0014] The second objective of this invention is to provide a method for preparing modified EMT molecular sieves, comprising: mixing an EMT molecular sieve or a solution containing an EMT molecular sieve (preferably a solution containing an EMT molecular sieve) with a silicon source I, a template agent I and an optional dispersant to obtain a dispersion, and performing a crystallization treatment on the dispersion to obtain the modified EMT molecular sieve.

[0015] In a preferred embodiment, the silicon source I is selected from at least one of silica sol and silicate ester, preferably silicate ester.

[0016] In a further preferred embodiment, the silicon source I is selected from at least one of silica sol and alkyl orthosilicate, preferably alkyl orthosilicate.

[0017] In a further preferred embodiment, the silicon source I is selected from at least one of silica sol, methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate, and butyl orthosilicate.

[0018] The inventors discovered through experiments that both silica sol and alkyl orthosilicates can achieve modification; however, alkyl orthosilicates showed better results than silica sol. The reason for this is likely that alkyl orthosilicates result in smaller and better-shaped silicon crystal particles on the molecular sieve surface.

[0019] In a preferred embodiment, the weight ratio of the silicon source I to the EMT molecular sieve is (0.5-4):10, preferably (1-2):10, wherein the weight of the silicon source I is based on its silica content.

[0020] For example, the weight ratio of the silicon source I to the EMT molecular sieve is 0.5:10, 1:10, 1.5:10, 2:10, 2.5:10, 3:10, 3.5:10 or 4:10, wherein the weight of the silicon source I is based on its silica content.

[0021] In a preferred embodiment, the template agent I is selected from at least one of tetrapropylammonium bromide and tetrapropylammonium hydroxide.

[0022] In a further preferred embodiment, the weight ratio of the template agent I (on a dry basis) to the silicon source I (on a SiO2 basis) is (1-5):10, preferably (2-4):10, wherein the weight of the template agent I is on a dry basis and the weight of the silicon source I is on a SiO2 basis.

[0023] For example, the weight ratio of the template agent I (on a dry basis) to the silicon source I (as SiO2) is 1:10, 2:10, 3:10, 4:10, or 5:10, wherein the weight of the template agent I is on a dry basis, and the weight of the silicon source I is as SiO2. "On a dry basis" refers to the portion after removing moisture.

[0024] In a preferred embodiment, the dispersant is selected from water; and / or, the EMT molecular sieve-containing solution is an aqueous solution containing EMT molecular sieve.

[0025] In a preferred embodiment, the crystallization treatment temperature is 70–90°C, for example, 70°C, 75°C, 80°C, 85°C, or 90°C.

[0026] In a further preferred embodiment, the temperature of the crystallization treatment is lower than the crystallization temperature or crystallization temperature during the preparation of the EMT molecular sieve, preferably 10-35°C lower, more preferably 20-30°C lower, for example 10°C, 25°C, 20°C, 25°C, 30°C or 35°C lower.

[0027] The crystallization temperature should not be too high, otherwise it may cause surface dissolution or crystal transformation of the EMT molecular sieve matrix.

[0028] In a preferred embodiment, post-processing is performed after the crystallization process.

[0029] In a further preferred embodiment, the post-processing includes filtration, washing, drying, calcination, and optional exchange.

[0030] In a further preferred embodiment, the filtration is vacuum filtration; and / or, washing with water to pH 7; and / or, the drying is natural air drying or oven drying; and / or, the calcination is carried out in an air atmosphere at 400°C to 700°C; and / or, the exchange is acid exchange and / or ammonium exchange.

[0031] The acid exchange and / or ammonium exchange can be carried out using conventional methods, such as an exchange temperature of 90°C and a solution concentration of 5-10%.

[0032] In a preferred embodiment, the preparation method includes: (1) mixing EMT molecular sieve or a solution containing EMT molecular sieve with silicon source I and stirring (preferably 1-20 h, more preferably 5-15 h); (2) adding template agent I and optional dispersion to obtain the dispersion; (3) crystallizing the dispersion; and (4) obtaining the modified EMT molecular sieve after post-treatment.

[0033] In a preferred embodiment, the EMT molecular sieve can be prepared directly using existing technologies.

[0034] In a preferred embodiment, the EMT-containing molecular sieve solution is obtained as follows: a crystallized solution containing EMT molecular sieve is obtained during the preparation of the EMT molecular sieve, which is the EMT-containing molecular sieve solution; optionally, the solid phase is further filtered to obtain the solid phase, and then the solid phase is mixed with water to obtain the EMT-containing molecular sieve solution; optionally, the solid phase is further dried to obtain dried EMT, and then the dried EMT is mixed with water to obtain the EMT-containing molecular sieve solution.

[0035] In this invention, it is preferable to use a crystallization solution containing EMT molecular sieves obtained during the preparation of EMT molecular sieves, because it contains residual 18-crown ether-6, which has a significant promoting effect on the uniformity of the formation of low-content crystalline phase layers; while filtration will only retain 18-crown ether-6 in the molecular sieve; if further drying (or calcination, which will almost completely decompose the residual 18-crown ether-6) will further volatilize the 18-crown ether-6 remaining in the molecular sieve, which is not conducive to the formation of a uniform and dense silicon crystalline phase and the acquisition of its good properties.

[0036] In a further preferred embodiment, the solution containing the EMT molecular sieve is obtained as follows:

[0037] (1.1) Mix aluminum source, silicon source II, sodium hydroxide, template agent II, solvent and optional additives to obtain mixture A;

[0038] (1.2) The mixture A is subjected to crystallization treatment to obtain crystallized liquid, which is the solution containing EMT molecular sieve.

[0039] In a preferred embodiment, the aluminum source is selected from at least one of sodium aluminate, aluminum nitrate, aluminum sulfate, aluminum sol, and boehmite.

[0040] In a preferred embodiment, the silicon source II is selected from at least one of sodium silicate, silica sol, silica fume, and water glass.

[0041] In a further preferred embodiment, the molar ratio of the silicon source II to the aluminum source is (8-11):1, preferably (10-11):1, wherein the molar amount of the silicon source II is calculated based on the molar amount of SiO2, and the molar amount of the aluminum source is calculated based on the molar amount of Al2O3.

[0042] For example, the molar ratio of the silicon source II to the aluminum source is 8:1, 9:1, 10:1 or 11:1, wherein the molar amount of the silicon source II is measured in terms of the molar amount of SiO2, and the molar amount of the aluminum source is measured in terms of the molar amount of Al2O3.

[0043] In a preferred embodiment, the template agent II is 18-crown ether-6.

[0044] In this process, 18-crown ether-6 plays a crucial role as a template agent in the high-temperature synthesis of EMT molecular sieves, and its dosage is usually relatively large. While the dosage can be significantly reduced with the addition of sodium phosphate, the molar ratio to the aluminum source (based on Al2O3) remains at (0.2–1):1. Furthermore, the inventors discovered in their experiments that, as a good complexing agent, 18-crown ether-6 can ensure the uniform distribution of silicon source I, template agent I, and other materials during crystallization, resulting in a more uniform and dense silicon crystalline phase layer on the surface. This makes the modified EMT molecular sieve less prone to clogging and extends its lifespan.

[0045] In a further preferred embodiment, the molar ratio of the template agent II to the aluminum source is (0.2-1):1, preferably (0.33-0.7):1, wherein the molar amount of the template agent II is expressed as the molar amount of its molecules, and the molar amount of the aluminum source is expressed as the molar amount of Al2O3 therein.

[0046] For example, the molar ratio of the template agent II to the aluminum source is 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1 or 1:1.

[0047] In a preferred embodiment, the solvent is water.

[0048] In a further preferred embodiment, the molar ratio of the solvent to the aluminum source is (100-400):1, preferably (120-200):1, wherein the molar amount of the solvent is expressed as the molar amount of its molecules, and the molar amount of the aluminum source is expressed as the molar amount of Al2O3 therein.

[0049] For example, the molar ratio of the solvent to the aluminum source is 100:1, 150:1, 200:1, 250:1, 300:1, 350:1 or 400:1, wherein the molar amount of the solvent is expressed as the molar amount of its molecules, and the molar amount of the aluminum source is expressed as the molar amount of Al2O3 therein.

[0050] In a preferred embodiment, the molar ratio of sodium hydroxide to the aluminum source is (1-3):1, preferably (1.5-2.5):1, wherein the molar amount of sodium hydroxide is expressed as the molar amount of Na2O, and the molar amount of the aluminum source is expressed as the molar amount of Al2O3.

[0051] For example, the molar ratio of sodium hydroxide to the aluminum source is 1:1, 2:1, or 3:1, wherein the molar amount of sodium hydroxide is expressed as the molar amount of Na2O, and the molar amount of the aluminum source is expressed as the molar amount of Al2O3.

[0052] In a preferred embodiment, the additive is selected from inorganic salt emulsifiers.

[0053] In a further preferred embodiment, the inorganic salt emulsifier is selected from at least one of sodium phosphate, sodium dipolyphosphate, and sodium pentapolyphosphate.

[0054] In a further preferred embodiment, when an additive is used, the molar ratio of the additive to the aluminum source is (0.02-0.1):1, preferably (0.03-0.05):1, wherein the molar amount of the additive is calculated as the molar amount of Na3PO4, and the molar amount of the aluminum source is calculated as the molar amount of Al2O3.

[0055] For example, when an additive is used, the molar ratio of the additive to the aluminum source is 0.02:1, 0.03:1, 0.04:1, 0.05:1, 0.06:1, 0.07:1, 0.08:1, 0.09:1, or 0.1:1.

[0056] In a preferred embodiment, the crystallization temperature in step (1.2) is 80–130°C, and the time is 0.5–5 days.

[0057] For example, the crystallization temperature in step (1.2) is 80°C, 90°C, 100°C, 110°C, 120°C or 130°C, and the time is 0.5d, 1d, 1.5d, 2d, 2.5d, 3d, 3.5d, 4d, 4.5d or 5d.

[0058] In a further preferred embodiment, the crystallization temperature in step (1.2) is 90–110°C, and the time is 2–3 days.

[0059] In a preferred embodiment, the method for preparing the modified EMT molecular sieve includes:

[0060] (a) Mix aluminum source, silicon source II, sodium hydroxide, template agent II, solvent and optional additives to obtain mixture A;

[0061] (b) The mixture A is subjected to crystallization treatment to obtain a crystallized solution;

[0062] (c) Add the silicon source I to the crystallization solution, stir for a set time, and then add the template agent I to obtain a dispersion;

[0063] (d) The dispersion is subjected to crystallization treatment, and then the post-treatment is performed to obtain the modified EMT molecular sieve.

[0064] In a preferred embodiment, the temperature of the crystallization process in step (d) is lower than the temperature of the crystallization process in step (b).

[0065] In a further preferred embodiment, the temperature of the crystallization treatment in step (d) is 10 to 35°C lower than the temperature of the crystallization treatment in step (b), more preferably 20 to 30°C lower, for example, 10°C, 25°C, 20°C, 25°C, 30°C, or 35°C lower.

[0066] The third objective of this invention is to provide a modified EMT molecular sieve obtained by the preparation method described in the second objective of this invention.

[0067] The fourth objective of this invention is to provide a catalyst comprising a binder and the modified EMT molecular sieve described in the first objective of this invention or the modified EMT molecular sieve obtained by the preparation method described in the second objective of this invention.

[0068] In a preferred embodiment, the binder is selected from at least one of alumina, alumina sol, silica sol, and clay.

[0069] In a preferred embodiment, based on a total weight of 100 wt% of the binder and the modified EMT molecular sieve, the content of the binder is 20-40 wt%, and the content of the modified EMT molecular sieve is 60-80 wt%.

[0070] For example, based on a total weight of 100 wt% of the binder and the modified EMT molecular sieve, the content of the binder is 20 wt%, 25 wt%, 30 wt%, 35 wt%, or 40 wt%, and the content of the modified EMT molecular sieve is 60 wt%, 65 wt%, 70 wt%, 75 wt%, or 80 wt%.

[0071] In a further preferred embodiment, based on a total weight of 100 wt% of the binder and the modified EMT molecular sieve, the content of the binder is 20-30 wt%, and the content of the modified EMT molecular sieve is 70-80 wt%.

[0072] The fifth objective of this invention is to provide the application of the modified EMT molecular sieve described in the first objective of this invention, the modified 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 in deolefination or reduction of the bromine index of aromatic materials, for example, in the deolefination of aqueous materials or reduction of the bromine index of aromatic materials.

[0073] The aqueous aromatic hydrocarbons contain water but no gum, and they originate from the aromatic hydrocarbon extraction unit in the aromatic hydrocarbon complex [specifically, the material extracted from the top of the deheptane tower (in the aromatic hydrocarbon extraction unit)]. (1) The aqueous aromatic hydrocarbons contain a certain amount of olefin impurities. Olefins are active and not only easily polymerize, but may also react with other components to generate non-ideal components, thus having a significant impact on the quality of aromatic hydrocarbon products. (2) Some petrochemical processes, such as xylene adsorption separation processes, are particularly sensitive to olefins. Even if the content of olefin impurities is only a few parts per million, it will have a very adverse effect on the process.

[0074] In a preferred embodiment, the water content in the aqueous material (e.g., aromatic material) is 50 to 400 ppm, for example, 50 ppm, 100 ppm, 150 ppm, 200 ppm, 250 ppm, 300 ppm, 350 ppm or 400 ppm.

[0075] In a preferred embodiment, the deolefination reaction is carried out at a temperature of 150–270°C and a pressure of 0.6 MPa–3.0 MPa.

[0076] For example, the reaction temperature for the deolefination is 150°C, 160°C, 180°C, 200°C, 220°C, 240°C, 260°C, or 270°C, and the pressure is 0.6 MPa, 0.8 MPa, 1 MPa, 1.2 MPa, 1.5 MPa, 1.8 MPa, 2 MPa, 2.2 MPa, 2.5 MPa, 2.8 MPa, or 3.0 MPa.

[0077] 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.

[0078] Compared with the prior art, the present invention has the following beneficial effects:

[0079] (1) The present invention uses a simple method to modify a layer of silicon crystalline phase on the surface of EMT molecular sieve to obtain modified EMT molecular sieve;

[0080] (2) The modified EMT molecular sieve can be used to treat water-containing materials at high temperatures, such as to perform deolefin treatment on aromatic materials. Detailed Implementation

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] The method for estimating the surface silicon crystal phase layer coverage is as follows: XPS is used to determine the silicon-to-aluminum ratio of the EMT matrix, the surface silicon crystal phase layer is based on pure silicon, and the silicon-to-aluminum ratio of the modified EMT molecular sieve is then determined. The surface silicon crystal phase layer coverage is calculated based on the difference between the two silicon-to-aluminum ratios.

[0086] The incremental method calculation refers to taking the mass of the calcined EMT molecular sieve as a baseline, subtracting the baseline value from the calcined modified EMT molecular sieve, and the increase in mass is the mass of the surface silicon crystal phase layer. The ratio of this increment to the mass of the modified EMT molecular sieve is the proportion of the weight of the silicon crystal layer to the total mass of the modified molecular sieve.

[0087]

Example 1

[0088] 12.44 g of sodium aluminate, 0.95 g of sodium phosphate, and 3.59 g of sodium hydroxide were dissolved in 60 g of distilled water to obtain solution i. 75 g of silica sol (40% by weight of SiO2), 8.72 g of 18-crown ether-6, and 20 g of water were mixed and stirred evenly to obtain solution ii. Solution i was then slowly added to solution ii under magnetic stirring to form a mixture. The molar ratio of the mixture was controlled to be Al2O3:SiO2:Na2O:Na3PO4:18-crown ether-6:H2O = 1:10:1.9:0.05:0.66:140. The mixture was crystallized at 110 °C for 3 days to obtain a crystallization solution. After filtration, washing, drying, and calcination, 38 g of EMT molecular sieve dry basis was obtained with a surface silicon-to-aluminum ratio of 3.9.

[0089] The above process was repeated to obtain an EMT molecular sieve crystallization solution. 24.3 g of tetraethyl orthosilicate (the weight ratio of SiO2 to EMT in tetraethyl orthosilicate was 1.8:10) was added to the crystallization solution, and the mixture was stirred at room temperature for 12 hours. Finally, 2.3 g of tetrapropylammonium bromide (TPABr) was added to obtain a dispersion. The dispersion was crystallized at 90℃ for 1 day. After crystallization, the mixture was filtered under reduced pressure, washed with distilled water until the pH reached 7, dried at 120℃, and calcined at 550℃ for 3 hours to obtain a modified EMT molecular sieve (named Si-EMT-1). The surface silicon-to-aluminum ratio was 18.8, and the estimated surface silicon crystalline phase layer coverage was 93.7%. Incremental calculations showed that the weight of the surface silicon crystalline layer accounted for 5 wt% of the total weight of the modified molecular sieve.

[0090] Si-EMT-1 and alumina were shaped and calcined according to a formulation of 80wt% and 20wt% by weight (dry basis) to obtain catalyst SE-1 for reducing the bromine index of aromatic feedstock.

[0091] Five g of the above-mentioned SE-1 catalyst was used to conduct an aromatic non-hydrogenated deolefination experiment in a fixed-bed reactor. The feedstock was a benzene-toluene mixture containing 300 ppm water and a bromine index of 260 mgBr / 100 g oil. The reaction was carried out at a temperature of 150 °C, a pressure of 2.0 MPa, and a space velocity of 25.0. -1 With an export bromine index of 20 mgBr / 100g oil as the standard, the reaction stability reached 375 hours.

[0092]

Example 2

[0093] 33.3 g of aluminum sulfate octahydrate, 0.57 g of sodium phosphate, and 6.8 g of sodium hydroxide were dissolved in 60 g of distilled water to obtain solution i. 30 g of silica, 4.4 g of 18-crown ether-6, and 65 g of water were mixed and stirred evenly to obtain solution ii. Solution i was then slowly added to solution ii under magnetic stirring to form a mixture. The molar ratio of the mixture was controlled to be Al2O3:SiO2:Na2O:Na3PO4:18-crown ether-6:H2O = 1:10:1.7:0.03:0.33:155. The mixture was crystallized at 110℃ for 2 days to obtain a crystallized solution. After filtration, washing, drying, and calcination, 33 g of EMT molecular sieve (dry basis) with a surface silicon-to-aluminum ratio of 3.7 was obtained.

[0094] The above process was repeated to obtain an EMT molecular sieve crystallization solution. 15.5 g of tetraethyl orthosilicate (the weight ratio of SiO2 to EMT in tetraethyl orthosilicate was 1.3:10) was added to the crystallization solution, and the mixture was stirred at room temperature for 12 hours. Finally, 3.5 g of tetrapropylammonium hydroxide (TPAOH, 25%) was added to obtain a dispersion. The dispersion was crystallized at 90 °C for 2 days. After crystallization, the mixture was filtered under reduced pressure, washed with distilled water until the pH reached 7, dried at 120 °C, and calcined at 550 °C for 3 hours to obtain a modified EMT molecular sieve (named Si-EMT-2). The surface silicon-to-aluminum ratio was 13.9, and the estimated surface silicon crystalline phase layer coverage was 91.1%. The incremental method calculation results showed that the weight of the surface silicon crystalline layer accounted for 3.5 wt% of the total weight of the modified molecular sieve.

[0095] Si-EMT-2 and alumina were shaped and calcined according to a formulation of 80wt% and 20wt% by weight (dry basis) to obtain catalyst SE-2 for reducing the bromine index of aromatic feedstock.

[0096] Five g of the above-mentioned SE-2 catalyst was used in a fixed-bed reactor for a non-hydrogenated deolefins test of reformed oil. The feedstock was a benzene-toluene mixture containing 300 ppm water and a bromine index of 260 mgBr / 100 g oil. The reaction was conducted at a temperature of 150 °C, a pressure of 2.0 MPa, and a space velocity of 25.0. -1 With an export bromine index of 20 mgBr / 100g oil as the standard, the reaction stability reached 290 hours.

[0097]

Example 3

[0098] 12.44 g of sodium aluminate, 0.18 g of sodium tripolyphosphate, and 5.58 g of sodium hydroxide were dissolved in 96 g of distilled water to obtain solution i. 115 g of tetraethyl orthosilicate, 6.6 g of 18-crown ether-6, and 68 g of water were mixed and stirred evenly to obtain solution ii. Solution i was then slowly added to solution ii under magnetic stirring to form a mixture. The molar ratio of the mixture was controlled to be Al2O3:SiO2:Na2O:Na3PO4:18-crown ether-6:H2O = 1:10.9:2.4:0.03:0.5:180. The mixture was crystallized at 110℃ for 2 days to obtain a crystallized solution. After filtration, washing, drying, and calcination, 30 g of EMT molecular sieve (dry basis) with a surface silicon-to-aluminum ratio of 4.3 was obtained.

[0099] The above process was repeated to obtain an EMT molecular sieve crystallization solution. 30g of silica sol (40% by weight of SiO2) was added to the crystallization solution (the weight ratio of SiO2 to EMT in the silica sol was 4:10). The mixture was stirred at room temperature for 10 hours. Finally, 19.2g of tetrapropylammonium hydroxide (TPAOH, 25%) was added to obtain a dispersion. The dispersion was crystallized at 80℃ for 7 days. After crystallization, the mixture was filtered under reduced pressure, washed with distilled water until the pH reached 7, dried at 120℃, and calcined at 550℃ for 3 hours to obtain a modified EMT molecular sieve (named Si-EMT-3). The surface silicon-to-aluminum ratio was 55.9, and the estimated surface silicon crystalline phase layer coverage was 98.1%. Incremental calculations showed that the weight of the surface silicon crystalline layer accounted for 9wt% of the total weight of the modified molecular sieve.

[0100] Si-EMT-3 and alumina were shaped and calcined according to a formulation of 80wt% and 20wt% by weight (dry basis) to obtain catalyst SE-3 for reducing the bromine index of aromatic feedstock.

[0101] Five g of the above-mentioned SE-3 catalyst was used in a fixed-bed reactor for a non-hydrogenated deolefins test of reformed oil. The feedstock was a benzene-toluene mixture containing 300 ppm water and a bromine index of 260 mgBr / 100 g oil. The reaction was conducted at a temperature of 150 °C, a pressure of 2.0 MPa, and a space velocity of 25.0. -1 With an export bromine index of 20 mgBr / 100g oil as the standard, the reaction stability reached 445 hours.

[0102]

Example 4

[0103] The preparation process of EMT molecular sieve is the same as in Example 1.

[0104] 12.44 g of sodium aluminate, 0.95 g of sodium phosphate, and 3.59 g of sodium hydroxide were dissolved in 60 g of distilled water to obtain solution i. 75 g of silica sol (40% by weight of SiO2), 8.72 g of 18-crown ether-6, and 20 g of water were mixed and stirred evenly to obtain solution ii. Then, solution i was slowly added to solution ii under magnetic stirring to form a mixture. The molar ratio of the mixture was controlled to be Al2O3:SiO2:Na2O:Na3PO4:18-crown ether-6:H2O = 1:10:1.9:0.05:0.66:140. The mixture was crystallized at 110℃ for 3 days to obtain a crystallization solution. After filtration, EMT molecular sieve filter cake was obtained.

[0105] 50g of water was added to the filter cake, stirred, and then 24.3g of tetraethyl orthosilicate (the weight ratio of SiO2 to EMT in tetraethyl orthosilicate was 1.8:10). The mixture was stirred at room temperature for 12 hours, and finally 2.3g of tetrapropylammonium bromide (TPABr) was added to obtain a dispersion. The dispersion was crystallized at 90℃ for 1 day. After crystallization, the mixture was filtered under reduced pressure, washed with distilled water until the pH reached 7, dried at 120℃, and calcined at 550℃ for 3 hours to obtain a modified EMT molecular sieve (named Si-EMT-4). The surface silicon-to-aluminum ratio was 14.5, and the estimated surface silicon crystalline phase layer coverage was 91.4%. The incremental method calculation results showed that the weight of the surface silicon crystalline layer accounted for 4wt% of the total weight of the modified molecular sieve.

[0106] Si-EMT-4 and alumina were shaped and calcined according to a formulation of 80wt% and 20wt% by weight (dry basis) to obtain catalyst SE-4 for reducing the bromine index of aromatic feedstock.

[0107] Five g of the above-mentioned SE-4 catalyst was used in a fixed-bed reactor for a non-hydrogenated deolefins test of reformed oil. The feedstock was a benzene-toluene mixture containing 300 ppm water and a bromine index of 260 mgBr / 100 g oil. The reaction was conducted at a temperature of 150 °C, a pressure of 2.0 MPa, and a space velocity of 25.0. -1 With an export bromine index of 20 mgBr / 100g oil as the standard, the reaction stability reached 330 hours.

[0108]

Example 5

[0109] The preparation process of EMT molecular sieve is the same as in Example 1.

[0110] 12.44 g of sodium aluminate, 0.95 g of sodium phosphate, and 3.59 g of sodium hydroxide were dissolved in 60 g of distilled water to obtain solution i. 75 g of silica sol (40% by weight of SiO2), 8.72 g of 18-crown ether-6, and 20 g of water were mixed and stirred evenly to obtain solution ii. Solution i was then slowly added to solution ii under magnetic stirring to form a mixture. The molar ratio of the mixture was controlled to be Al2O3:SiO2:Na2O:Na3PO4:18-crown ether-6:H2O = 1:10:1.9:0.05:0.66:140. The mixture was crystallized at 110 °C for 3 days to obtain a crystallization solution. After filtration, an EMT molecular sieve filter cake was obtained, dried at 100 °C for 12 hours, and then pulverized.

[0111] 85g of water was added to the EMT molecular sieve powder, and after stirring, 24.3g of tetraethyl orthosilicate (the weight ratio of SiO2 to EMT in tetraethyl orthosilicate was 1.8:10) was added. The mixture was stirred at room temperature for 12 hours, and finally 2.3g of tetrapropylammonium bromide (TPABr) was added to obtain a dispersion. The dispersion was crystallized at 90℃ for 1 day. After crystallization, the mixture was filtered under reduced pressure, washed with distilled water until the pH reached 7, dried at 120℃, and calcined at 550℃ for 3 hours to obtain a modified EMT molecular sieve (named Si-EMT-5). The surface silicon-to-aluminum ratio was 11.0, and the estimated surface silicon crystalline phase layer coverage was 87.7%. The incremental method calculation results showed that the weight of the surface silicon crystalline layer accounted for 3.3wt% of the total weight of the modified molecular sieve.

[0112] Si-EMT-5 and alumina were shaped and calcined according to a formulation of 80wt% and 20wt% by weight (dry basis) to obtain catalyst SE-5 for reducing the bromine index of aromatic feedstock.

[0113] Five g of the above-mentioned SE-5 catalyst was used in a fixed-bed reactor for a non-hydrogenated deolefins test of reformed oil. The feedstock was a benzene-toluene mixture containing 300 ppm water and a bromine index of 260 mgBr / 100 g oil. The reaction was conducted at a temperature of 150 °C, a pressure of 2.0 MPa, and a space velocity of 25.0. -1 With an export bromine index of 20 mgBr / 100g oil as the standard, the reaction stability reached 252 hours.

[0114] Through experiments, the inventors discovered that the coverage of the silicon crystal phase layer on the surface of the modified EMT molecular sieve decreases after filtration and drying, possibly due to the low concentration of 18-crown ether-6 in the solution during secondary crystallization.

[0115] Comparative Example 1

[0116] The preparation process of EMT molecular sieve is the same as in Example 1.

[0117] 12.44 g of sodium aluminate, 0.95 g of sodium phosphate, and 3.59 g of sodium hydroxide were dissolved in 60 g of distilled water to obtain solution i. 75 g of silica sol (SiO2 weight percentage 40%), 8.72 g of 18-crown ether-6, and 20 g of water were mixed and stirred evenly to obtain solution ii. Solution i was then slowly added to solution ii under magnetic stirring to form a mixture. The molar ratio of the mixture was controlled to be Al2O3:SiO2:Na2O:Na3PO4:18-crown ether-6:H2O = 1:10:1.9:0.05:0.66:140. The mixture was crystallized at 110 °C for 3 days to obtain a crystallized solution. After vacuum filtration and washing with distilled water until the pH reached 7, the filter cake was dried at 120 °C and calcined at 550 °C for 3 hours to obtain EMT molecular sieve (named EMT-D1).

[0118] EMT-D1 and alumina were shaped and calcined according to a formulation of 80wt% and 20wt% by weight (dry basis) to obtain catalyst E-D1 for reducing the bromine index of aromatic feedstock.

[0119] Five g of the above E-D1 catalyst was used in a fixed-bed reactor for a non-hydrogenated deolefins test of reformed oil. The feedstock was a benzene-toluene mixture containing 300 ppm water and a bromine index of 260 mgBr / 100 g oil. The reaction was conducted at 150 °C, 2.0 MPa, and a space velocity of 25.0. -1 With an export bromine index of 20 mgBr / 100g oil as the standard, the reaction stability was 96 hours.

[0120] Comparative Example 2

[0121] The EMT molecular sieve filter cake obtained in Example 4 was impregnated with 24.3 g of tetraethyl orthosilicate in an equal volume, dried at 120 °C, and calcined at 550 °C for 3 hours to obtain a modified EMT molecular sieve (named Si-EMT-D1). The surface silicon-to-aluminum ratio was 103, and the estimated surface silica coverage was 99%. The incremental calculation results showed that the surface silica accounted for 13 wt% of the total weight of the modified molecular sieve.

[0122] According to the formulation of 80wt% and 20wt% by weight dry basis, Si-EMT-D1 and alumina were shaped and calcined to obtain the catalyst SE-D1 for reducing the bromine index of aromatic feedstock.

[0123] Five g of the above-mentioned SE-D1 catalyst was used in a fixed-bed reactor for a non-hydrogenated deolefins test of reformed oil. The feedstock was a benzene-toluene mixture containing 300 ppm water and a bromine index of 260 mgBr / 100 g oil. The reaction was conducted at a temperature of 150 °C, a pressure of 2.0 MPa, and a space velocity of 25.0. -1 The reaction stability was 12 hours, based on an export bromine index of 20 mgBr / 100g oil.

[0124] Comparative Example 3

[0125] The preparation process of EMT molecular sieve is the same as in Example 1.

[0126] 12.44 g of sodium aluminate, 0.95 g of sodium phosphate, and 3.59 g of sodium hydroxide were dissolved in 60 g of distilled water to obtain solution i. 75 g of silica sol (40% by weight of SiO2), 8.72 g of 18-crown ether-6, and 20 g of water were mixed and stirred evenly to obtain solution ii. Solution i was then slowly added to solution ii under magnetic stirring to form a mixture. The molar ratio of the mixture was controlled to be Al2O3:SiO2:Na2O:Na3PO4:18-crown ether-6:H2O = 1:10:1.9:0.05:0.66:140. The mixture was crystallized at 110 °C for 3 days to obtain a crystallized solution. After vacuum filtration, an EMT molecular sieve filter cake was obtained, dried at 100 °C for 12 hours, calcined at 550 °C for 3 hours, and then pulverized.

[0127] 120g of water was added to the EMT molecular sieve powder, and after stirring, 24.3g of tetraethyl orthosilicate (the weight ratio of SiO2 to EMT in tetraethyl orthosilicate was 1.8:10) was added. The mixture was stirred at room temperature for 12 hours, and finally 2.3g of tetrapropylammonium bromide (TPABr) was added to obtain a dispersion. The dispersion was crystallized at 90℃ for 1 day. After crystallization, the mixture was filtered under reduced pressure, washed with distilled water until the pH reached 7, dried at 120℃, and calcined at 550℃ for 3 hours to obtain a modified EMT molecular sieve (named Si-EMT-5). The surface silicon-to-aluminum ratio was 5.1, and the estimated surface silicon crystalline phase layer coverage was 53.5%. The incremental method calculation results showed that the weight of the surface silicon crystalline layer accounted for 1.7wt% of the total weight of the modified molecular sieve.

[0128] Si-EMT-D3 and alumina were shaped and calcined according to a formulation of 80wt% and 20wt% by weight (dry basis) to obtain SE-D3, a catalyst for reducing the bromine index of aromatic feedstocks.

[0129] Five g of the above-mentioned SE-D3 catalyst was used in a fixed-bed reactor for a non-hydrogenated deolefins test of reformed oil. The feedstock was a benzene-toluene mixture containing 300 ppm water and a bromine index of 260 mgBr / 100 g oil. The reaction was conducted at a temperature of 150 °C, a pressure of 2.0 MPa, and a space velocity of 25.0. -1 With an export bromine index of 20 mgBr / 100g oil as the standard, the reaction stability was 144 hours.

[0130] 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. A modified EMT molecular sieve, comprising an EMT molecular sieve matrix and a silicon crystal phase layer located on the surface of the EMT molecular sieve matrix, wherein the silicon crystal phase layer has a coverage of more than 85% on the surface of the EMT molecular sieve matrix; the preparation method of the modified EMT molecular sieve includes: A solution containing EMT molecular sieve is mixed with silicon source I, template agent I, and optional dispersant to obtain a dispersion. The dispersion is then subjected to crystallization treatment at a temperature of 70~90℃ to obtain the modified EMT molecular sieve. The solution containing EMT molecular sieve is obtained as follows: Step (1.1) Aluminum source, silicon source II, sodium hydroxide, template agent II, solvent, and optional additives are mixed to obtain mixture A. Template agent II is 18-crown ether-6. Step (1.2) Mixture A is subjected to crystallization treatment to obtain a crystallized liquid, which is the solution containing EMT molecular sieve.

2. The modified EMT molecular sieve according to claim 1, characterized in that, Based on the modified EMT molecular sieve being 100 wt%, the silicon crystal phase layer accounts for 2 to 20 wt%.

3. The modified EMT molecular sieve according to claim 1, characterized in that, Based on the modified EMT molecular sieve being 100 wt%, the silicon crystal phase layer accounts for 3 to 10 wt%.

4. A method for preparing modified EMT molecular sieves, comprising: A solution containing EMT molecular sieve is mixed with silicon source I, template agent I, and optional dispersant to obtain a dispersion. The dispersion is then subjected to crystallization treatment at a temperature of 70~90℃ to obtain the modified EMT molecular sieve. The solution containing EMT molecular sieve is obtained as follows: Step (1.1) Aluminum source, silicon source II, sodium hydroxide, template agent II, solvent, and optional additives are mixed to obtain mixture A. Template agent II is 18-crown ether-6. Step (1.2) Mixture A is subjected to crystallization treatment to obtain a crystallized liquid, which is the solution containing EMT molecular sieve.

5. The preparation method according to claim 4, characterized in that, The silicon source I is selected from at least one of silica sol and silicate ester.

6. The preparation method according to claim 4, characterized in that, The silicon source I is selected from at least one of silica sol and alkyl orthosilicate.

7. The preparation method according to claim 4, characterized in that, The silicon source I is selected from at least one of silica sol, methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate, and butyl orthosilicate.

8. The preparation method according to claim 4, characterized in that, The weight ratio of silicon source I to the EMT molecular sieve is (0.5~4):10, wherein the weight of silicon source I is based on its silica content.

9. The preparation method according to claim 4, characterized in that, The weight ratio of silicon source I to the EMT molecular sieve is (1~2):10, wherein the weight of silicon source I is based on its silica content.

10. The preparation method according to claim 4, characterized in that, The template agent I is selected from at least one of tetrapropylammonium bromide and tetrapropylammonium hydroxide.

11. The preparation method according to claim 4, characterized in that, The weight ratio of the template agent I to the silicon source I is (1-5):10, wherein the weight of the silicon source I is SiO2.

12. The preparation method according to claim 4, characterized in that, The weight ratio of the template agent I to the silicon source I is (2-4):10, wherein the weight of the silicon source I is SiO2.

13. The preparation method according to claim 4, characterized in that, The dispersant is selected from water; and / or, The crystallization treatment temperature is lower than the crystallization temperature used to prepare the EMT molecular sieve; and / or The crystallization process is followed by post-processing, which includes filtration, washing, drying, and calcination.

14. The preparation method according to any one of claims 4 to 13, characterized in that, The preparation method includes: (1) mixing the solution containing EMT molecular sieve with silicon source I and stirring; (2) adding template agent I and optional dispersion to obtain the dispersion; (3) crystallizing the dispersion; and (4) obtaining the modified EMT molecular sieve after post-treatment.

15. The preparation method according to claim 4, characterized in that, The aluminum source is selected from at least one of sodium aluminate, aluminum nitrate, aluminum sulfate, aluminum sol, and boehmite; and / or, The silicon source II is selected from at least one of sodium silicate, silica sol, silica fume, and water glass; and / or, The solvent is water; and / or, The additives are selected from inorganic salt emulsifiers.

16. The preparation method according to claim 15, characterized in that, The additive is selected from at least one of sodium phosphate, sodium dipolyphosphate, and sodium pentapolyphosphate.

17. The preparation method according to claim 15, characterized in that, The molar ratio of the silicon source II to the aluminum source is (8~11):1, wherein the molar amount of the silicon source II is calculated based on the molar amount of SiO2, and the molar amount of the aluminum source is calculated based on the molar amount of Al2O3; and / or, The molar ratio of the template agent II to the aluminum source is (0.2~1):1, wherein the molar amount of the template agent II is expressed as the molar amount of its molecules, and the molar amount of the aluminum source is expressed as the molar amount of Al2O3 therein; and / or, The molar ratio of the solvent to the aluminum source is (100~400):1, wherein the molar amount of the solvent is expressed as the molar amount of its molecules, and the molar amount of the aluminum source is expressed as the molar amount of Al2O3 therein; and / or, The molar ratio of sodium hydroxide to the aluminum source is (1~3):1, wherein the molar amount of sodium hydroxide is expressed as the molar amount of Na2O, and the molar amount of the aluminum source is expressed as the molar amount of Al2O3; and / or, When an additive is used, the molar ratio of the additive to the aluminum source is (0.02~0.1):1, wherein the molar amount of the additive is calculated as the molar amount of Na3PO4, and the molar amount of the aluminum source is calculated as the molar amount of Al2O3.

18. The preparation method according to claim 15, characterized in that, The molar ratio of the silicon source II to the aluminum source is (10~11):1, wherein the molar amount of the silicon source II is calculated based on the molar amount of SiO2, and the molar amount of the aluminum source is calculated based on the molar amount of Al2O3; and / or, The molar ratio of the template agent II to the aluminum source is (0.33~0.7):1, wherein the molar amount of the template agent II is expressed as the molar amount of its molecules, and the molar amount of the aluminum source is expressed as the molar amount of Al2O3 therein; and / or, The molar ratio of the solvent to the aluminum source is (120~200):1, wherein the molar amount of the solvent is expressed as the molar amount of its molecules, and the molar amount of the aluminum source is expressed as the molar amount of Al2O3 therein; and / or, The molar ratio of sodium hydroxide to the aluminum source is (1.5~2.5):1, wherein the molar amount of sodium hydroxide is expressed as the molar amount of Na2O, and the molar amount of the aluminum source is expressed as the molar amount of Al2O3; and / or, When an additive is used, the molar ratio of the additive to the aluminum source is (0.03~0.05):1, wherein the molar amount of the additive is calculated as the molar amount of Na3PO4, and the molar amount of the aluminum source is calculated as the molar amount of Al2O3.

19. The preparation method according to claim 4, characterized in that, The crystallization temperature in step (1.2) is 80~130℃; and / or the crystallization time in step (1.2) is 0.5~5 days.

20. The preparation method according to claim 19, characterized in that, The crystallization temperature in step (1.2) is 90~110℃; and / or the crystallization time in step (1.2) is 2~3 days.

21. Modified EMT molecular sieve obtained by the preparation method according to any one of claims 4 to 20.

22. A catalyst comprising a binder and a modified EMT molecular sieve as described in any one of claims 1 to 3 or a modified EMT molecular sieve obtained by the preparation method described in any one of claims 4 to 20.

23. The catalyst according to claim 22, characterized in that, The binder is selected from at least one of alumina, alumina sol, silica sol, and clay.

24. The catalyst according to claim 22, characterized in that, Based on a total weight of 100wt% for the binder and the modified EMT molecular sieve, the content of the binder is 20-40wt%, and the content of the modified EMT molecular sieve is 60-80wt%.

25. The application of the modified EMT molecular sieve according to any one of claims 1 to 3, the modified EMT molecular sieve obtained by the preparation method according to any one of claims 4 to 20, or the catalyst according to any one of claims 22 to 24 in the deolefination of aqueous materials or the reduction of the bromine index of aromatic materials.

26. The application according to claim 25, characterized in that, The water content in the aqueous material is 50~400ppm.

27. The application according to claim 25, characterized in that, The deolefin reaction is carried out at a temperature of 150~270℃ and a pressure of 0.6MPa~3.0MPa.