A method for removing olefins from gum-containing aromatic hydrocarbons and the resulting gum-containing aromatic hydrocarbons

Abstract

This invention discloses a method for removing olefins from colloidal aromatic hydrocarbons and the resulting colloidal aromatic hydrocarbons. The method includes: contacting the colloidal aromatic hydrocarbons with a catalyst to perform deolefin removal, wherein the catalyst comprises a core-shell structured EMT molecular sieve and an optional binder. The core-shell structured EMT molecular sieve of this invention can be directly used for deolefin removal reactions of aromatic hydrocarbons with high colloidal content, without the need for the use of clay or other porous materials as upstream protectants.

Description

Technical Field

[0001] This invention belongs to the field of aromatic hydrocarbon deolefination, and particularly relates to the deolefination of aromatic hydrocarbons containing gum. Background Technology

[0002] Xylene is a basic raw material in the petrochemical industry, mainly derived from aromatic hydrocarbon complexes, and is a major product of the chemical sector. During xylene production, the products of the catalytic reforming reaction 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 xylene products.

[0003] 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 operation of subsequent processes, a refining process is necessary after the reforming process to remove trace amounts of olefin impurities.

[0004] After fractionation in the heptane removal tower, the bottom product of the reforming product not only has a high bromine index but also contains a significant amount of gum. Under normal operating conditions, the gum content in this product is required to be below 20 mg / 100 ml. However, under abnormal operating conditions or at the end of the reforming catalyst's lifespan, the gum content can increase significantly. Gum is generally a polycyclic or fused-ring substance composed of three or more benzene rings. Currently, in the non-hydrogenated olefin removal process of reforming oil, a clay tower is installed upstream of the molecular sieve catalyst to block gum and prevent rapid catalyst deactivation.

[0005] Mining bleaching clay causes permanent environmental damage. Deactivated bleaching clay containing aromatics 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 today, this issue is receiving growing attention from governments and people around the world. Summary of the Invention

[0006] To overcome the problems existing in the prior art, the present invention provides a method for removing olefins from colloidal aromatic hydrocarbons and the resulting aromatic hydrocarbons, wherein the colloidal aromatic hydrocarbons are contacted with a catalyst for olefin removal, and the catalyst includes a core-shell structured EMT molecular sieve and an optional binder; since the surface of the core-shell structured EMT molecular sieve contains a silicon crystal phase layer, it can prevent large molecular colloidal substances from entering the pores of the EMT molecular sieve, thereby slowing down the coking rate in the pores and extending the service life of the catalyst.

[0007] One objective of this invention is to provide a method for removing olefins from gum-containing aromatic hydrocarbons, comprising: contacting the gum-containing aromatic hydrocarbons with a catalyst to remove olefins, wherein the catalyst comprises a core-shell structured EMT molecular sieve and an optional binder.

[0008] The gums described in this invention are polycyclic or fused-ring macromolecules, which are the same concept as gums in conventional oils.

[0009] In a preferred embodiment, the content of gum in the gum-containing aromatic hydrocarbon is 30-200 mg / 100 ml.

[0010] In a further preferred embodiment, the content of gum in the gum-containing aromatic hydrocarbon is 50-150 mg / 100 ml, for example, 50, 80, 100, 120 or 150 mg / 100 ml.

[0011] The unit for the gum content is mg gum / 100ml of gum-containing aromatic hydrocarbons.

[0012] The aromatic hydrocarbons described in this invention contain gums. In existing aromatic hydrocarbon complexes, the gum content in the non-hydrogenated deolefins unit is typically controlled to be below 20 mg / 100 ml, and clay is used to adsorb most of the gums in the feed to protect the downstream catalyst. Under conditions of high gum content and high bromine index feedstock, using conventional deolefins catalysts alone will cause rapid catalyst deactivation.

[0013] In a preferred embodiment, the aromatic hydrocarbons in the colloidal aromatic hydrocarbons are C8 or higher aromatic hydrocarbons.

[0014] In a further preferred embodiment, the gum-containing aromatic hydrocarbons originate from the catalytic reforming unit in the aromatic hydrocarbon complex, preferably from the bottom liquid of the heptane removal tower in the catalytic reforming unit.

[0015] In a preferred embodiment, the conditions for deolefination include: a temperature of 150–270°C, and / or a pressure of 0.6–3.0 MPa, and / or a weight hourly space velocity (WHSV) of 2–25 h⁻¹ for the aromatic hydrocarbons. -1 .

[0016] For example, the deolefination temperature is 150°C, 180°C, 200°C, 220°C, 250°C, or 270°C; the deolefination pressure is 0.6 MPa, 1 MPa, 1.5 MPa, 2 MPa, 2.5 MPa, or 3.0 MPa; and / or, the weight hourly space velocity (WHSV) of the colloidal aromatic hydrocarbons is 2, 5, 10, 15, 20, or 25 h⁻¹. -1 .

[0017] In a further preferred embodiment, the conditions for deolefination include: a temperature of 150–220°C, and / or a pressure of 1–2.5 MPa, and / or a weight hourly space velocity (WHSV) of 5–15 h⁻¹ for the aromatic hydrocarbons. -1 .

[0018] In a preferred embodiment, the core-shell structured EMT molecular sieve includes an EMT molecular sieve core and a silicon crystal phase shell.

[0019] In a further preferred embodiment, the silicon crystal phase shell accounts for 1 to 20 wt% of the core-shell structured EMT molecular sieve, preferably 2 to 10 wt%, for example 1 wt%, 2 wt%, 5 wt%, 8 wt%, 10 wt%, 12 wt%, 15 wt%, 18 wt%, or 20 wt%.

[0020] In a further preferred embodiment, the silicon phase shell has a coverage of more than 85%, for example, 85%, 90%, 95% or 100%.

[0021] The method for estimating the coverage of the surface silicon crystal phase layer is as follows: XPS is used to determine the silicon-to-aluminum ratio of the EMT core, the surface silicon crystal phase layer shell is calculated as pure silicon, and the silicon-to-aluminum ratio of the core-shell structure EMT molecular sieve is then determined. The above ratio is calculated based on the difference between the two silicon-to-aluminum ratios.

[0022] In this invention, the silicon crystalline phase layer on the EMT surface is a high-silicon or pure-silicon molecular sieve with an MFI structure and a ten-membered ring structure. The colloidal material, being a polycyclic / fused-ring macromolecule, cannot enter the pores of the silicon crystalline phase layer. Olefin reactants can diffuse smoothly through the ten-membered ring into the internal EMT molecular sieve, and because the silicon crystalline phase layer is weakly acidic, the olefins will not react there. The products of the de-olefin reaction that occur on the internal EMT molecular sieve then diffuse out of the catalyst through the silicon crystalline phase layer. Therefore, the colloidal material has a relatively small impact on the performance of this modified EMT molecular sieve.

[0023] In a preferred embodiment, the binder is selected from at least one of alumina, alumina sol, silica sol, and clay.

[0024] In a preferred embodiment, when the catalyst contains a binder, the binder content is 20-40 wt% (e.g., 20 wt%, 25 wt%, 30 wt%, 35 wt%, or 40 wt%) based on 100 wt% of the total catalyst weight, and the core-shell structured EMT molecular sieve content is 60-80 wt% (e.g., 60 wt%, 65 wt%, 70 wt%, 75 wt%, or 80 wt%).

[0025] In a preferred embodiment, the core-shell structured EMT molecular sieve is prepared as follows:

[0026] (1) Obtain EMT molecular sieve, or, crystallize a dispersion A containing aluminum source, silicon source A, sodium hydroxide, template agent A, solvent and optional additives to obtain EMT molecular sieve crystallization solution.

[0027] (2) The EMT molecular sieve or the EMT molecular sieve crystallization solution is mixed with silicon source B, template agent B and optional dispersant to obtain dispersion B;

[0028] (3) The dispersion B is crystallized and then post-processed to obtain the core-shell structure EMT molecular sieve.

[0029] In a preferred embodiment, in step (1), the aluminum source is selected from at least one of sodium aluminate, aluminum nitrate, aluminum sulfate, aluminum sol, and boehmite.

[0030] In a preferred embodiment, in step (1), the silicon source A is selected from at least one of sodium silicate, silica sol, silica fume, and water glass, preferably silica sol.

[0031] In a further preferred embodiment, in step (1), the molar ratio of the silicon source A to the aluminum source is (8-11):1, preferably (10-11):1, wherein the molar amount of the silicon source A is calculated as the molar amount of SiO2, and the molar amount of the aluminum source is calculated as the molar amount of Al2O3.

[0032] For example, in step (1), the molar ratio of the silicon source A to the aluminum source is 8:1, 8.5:1, 9:1, 9.5:1, 10:1, 10.5:1 or 11:1, wherein the molar amount of the silicon source A is calculated as the molar amount of SiO2 therein, and the molar amount of the aluminum source is calculated as the molar amount of Al2O3 therein.

[0033] In a preferred embodiment, in step (1), the template agent A is selected from 18-crown ether-6.

[0034] This invention uses 18-crown ether-6 as a template agent to prepare EMT molecular sieve cores. Thus, 18-crown ether-6 will remain in the EMT molecular sieve crystallization solution obtained in step (1), serving the following functions: 18-crown ether-6 acts as a good complexing agent, ensuring uniform distribution of materials such as silicon source B and template agent B during the crystallization process in step (2), and forming a more uniform and dense silicon crystal phase layer on the core surface. This makes the core-shell structured EMT molecular sieve less prone to clogging and has a longer lifespan.

[0035] In a further preferred embodiment, in step (1), the molar ratio of the template agent A to the aluminum source is (0.2-1):1, preferably (0.33-0.7):1, wherein the molar amount of the template agent A 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.

[0036] The molar ratio of the template agent A to the aluminum source is 0.2:1, 0.4:1, 0.6:1, 0.8:1, or 1:1, wherein the molar amount of the template agent A 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.

[0037] In a preferred embodiment, in step (1), the solvent is water.

[0038] In a further preferred embodiment, in step (1), 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.

[0039] In step (1), 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.

[0040] In a preferred embodiment, in step (1), the additive is selected from inorganic salt emulsifiers, preferably from at least one of sodium phosphate, sodium dipolyphosphate, and sodium tripolyphosphate.

[0041] In a further preferred embodiment, in step (1), 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.

[0042] In step (1), the molar ratio of the additive to the aluminum source is 0.02:1, 0.04:1, 0.06:1, 0.08:1 or 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.

[0043] In a preferred embodiment, in step (1), 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.

[0044] For example, in step (1), the molar ratio of sodium hydroxide to the aluminum source is 1:1, 1.5:1, 2:1, 2.5:1 or 3:1.

[0045] In a further preferred embodiment, in step (1), 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.

[0046] In a preferred embodiment, in step (1), the temperature of the crystallization treatment is 80-130°C, preferably 90-110°C, for example 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C or 130°C.

[0047] In a further preferred embodiment, in step (1), the crystallization treatment time is 0.5 to 5 days, preferably 2 to 3 days, for example 0.5 days, 1 day, 2 days, 3 days, 4 days or 5 days.

[0048] In a preferred embodiment, in step (2), the EMT molecular sieve or a solution containing the EMT molecular sieve is first mixed with silicon source B and stirred, and then template agent B and optional dispersant are added to obtain the dispersion B.

[0049] In a further preferred embodiment, the stirring is carried out for 1 to 20 hours, preferably 5 to 15 hours, for example 1 hour, 2 hours, 5 hours, 8 hours, 10 hours, 12 hours, 15 hours, 18 hours or 20 hours.

[0050] In a preferred embodiment, in step (2), the silicon source B is selected from silica sol and / or silicate esters, preferably, the silicate ester is an alkyl orthosilicate.

[0051] In a further preferred embodiment, the silicon source B is selected from at least one of silica sol, methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate, and butyl orthosilicate.

[0052] Among them, the use of alkyl orthosilicates to form the shell is the most effective, possibly because alkyl orthosilicates can form a shell with smaller silicon crystal particles and more uniform coverage.

[0053] In a preferred embodiment, in step (2), the weight ratio of the silicon source B to the EMT molecular sieve is (0.5 to 4):10, for example, 0.5:10, 1:10, 2:10, 3:10 or 4:10; wherein the weight of the silicon source B is based on the SiO2 content therein.

[0054] In a further preferred embodiment, in step (2), the weight ratio of the silicon source B to the EMT molecular sieve is (1-2):10, wherein the weight of the silicon source B is based on its SiO2 content.

[0055] In a preferred embodiment, in step (2), the template agent B is selected from at least one of tetrapropylammonium bromide and tetrapropylammonium hydroxide.

[0056] In a further preferred embodiment, in step (2), the weight ratio of the template agent B to the silicon source B is (1-5):10, for example, 1:10, 1.5:10, 2:10, 2.5:10, 3:10, 3.5:10, 4:10, 4.5:10 or 5:10; wherein, the weight of the template agent B is on a dry basis (excluding moisture), and the weight of the silicon source B is based on the SiO2 content.

[0057] In a further preferred embodiment, in step (2), the weight ratio of the template agent B to the silicon source B is (2-4):10, wherein the weight of the template agent B is on a dry basis and the weight of the silicon source B is based on the SiO2 content.

[0058] In a preferred embodiment, in step (2), the dispersant is water.

[0059] In a preferred embodiment, in step (3), the temperature of the crystallization treatment is 70 to 90°C, for example, 70°C, 72°C, 75°C, 78°C, 80°C, 82°C, 85°C, 88°C or 90°C.

[0060] In a further preferred embodiment, the temperature of the crystallization treatment in step (3) is lower than the temperature of the crystallization treatment in step (1), preferably 10 to 35°C lower, for example, 10°C, 20°C, 30°C or 35°C lower.

[0061] If the crystallization temperature in step (3) is greater than that in step (1), it may cause the surface of the EMT molecular sieve core to dissolve or the crystal form to change.

[0062] In a preferred embodiment, in step (3), the post-processing includes filtration (e.g., vacuum filtration), washing (preferably washing to pH 7), drying, calcination, and optionally exchange.

[0063] In a further preferred embodiment, the calcination is carried out in an air atmosphere at 400°C to 700°C; and / or, the exchange includes acid exchange and / or ammonium exchange.

[0064] The exchange can be performed using methods disclosed in the prior art.

[0065] A second objective of this invention is to provide a resinous aromatic hydrocarbon obtained by processing using the method described in one objective of this invention.

[0066] 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.

[0067] Compared with the prior art, the present invention has the following beneficial effects:

[0068] (1) The silicon crystal phase layer on the surface of the core-shell structure EMT molecular sieve is uniformly distributed, and the silicon crystal phase layer coverage is high at low content.

[0069] (2) The core-shell structure EMT molecular sieve of the present invention can be directly used in the deolefination reaction of aromatic hydrocarbons with high content of colloids, without the need to use clay or other porous materials as upstream protectants. Detailed Implementation

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] 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 core, the surface silicon crystal phase layer is based on pure silicon, and the silicon-to-aluminum ratio of the core-shell structure EMT molecular sieve is then determined. The coverage of the surface silicon crystal phase layer is calculated based on the difference between the two silicon-to-aluminum ratios.

[0075] 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 core-shell structure 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 core-shell structure EMT molecular sieve is the proportion of the weight of the silicon crystal layer to the total weight of the modified molecular sieve.

[0076]

Example 1

[0077] Aluminum sulfate octahydrate, sodium phosphate, and sodium hydroxide (calculated as Na2O) were dissolved in distilled water to obtain solution i. Silica (calculated as SiO2), 18-crown ether-6, and water were mixed and stirred until homogeneous 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 = 1:10.9:1.7:0.05:0.66:170. The mixture was crystallized at 100℃ for 3 days to obtain a crystallized solution. After filtration, washing, drying, and calcination, 36 grams of EMT molecular sieve (dry basis) with a surface silicon-to-aluminum ratio of 4.1 was obtained.

[0078] 20 g of tetraethyl orthosilicate (the weight ratio of SiO2 to EMT in tetraethyl orthosilicate is 1.6:10) was added to the crystallization solution obtained above, and the mixture was stirred at room temperature for 12 hours. Finally, 5 g of tetrapropylammonium hydroxide (TPAOH, 25%) was added to obtain a dispersion. The dispersion was crystallized at 80 °C for 3 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 core-shell structured EMT molecular sieve S1 with a surface silicon-to-aluminum ratio of 13.3. The estimated surface silicon crystalline phase layer coverage was 90.2%. The incremental calculation results showed that the weight of the surface silicon crystalline layer accounted for 3 wt% of the total weight of the modified molecular sieve.

[0079] The core-shell structured EMT molecular sieve S1 and alumina were shaped and calcined according to a formulation of 80 wt% and 20 wt% by weight (dry basis) to obtain the deolefination catalyst S1.

[0080] Five g of the above-mentioned deolefination catalyst S1 was used in a fixed-bed reactor for a non-hydrogenated deolefination experiment. The feedstock was the bottom product of a heptane removal tower containing 80 mg / 100 ml of gum, with a bromine index of 1600 mgBr / 100 g oil. The reaction temperature was 170 °C, the reaction pressure was 2.0 MPa, and the weight hourly space velocity (WHSV) was 10.0 h⁻¹. -1 After 240 hours of reaction, the reactor outlet had a gum content of 73 mg / 100 ml and an outlet bromine index of 380 mgBr / 100 g oil.

[0081]

Example 2

[0082] Sodium aluminate, sodium phosphate, and sodium hydroxide (calculated as Na2O) were dissolved in distilled water to obtain solution i. Silica sol (SiO2 weight percentage 40%), 18-crown ether-6, and water were mixed and stirred until homogeneous 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 = 1:10:1.5:0.05:0.66:140. The mixture was crystallized at 100℃ for 4 days to obtain a crystallized solution. After filtration, washing, drying, and calcination, 32 g of EMT molecular sieve (dry basis) was obtained, with a surface silicon-to-aluminum ratio of 3.7.

[0083] The above process was repeated to obtain an EMT molecular sieve crystallization solution. 22 g of tetraethyl orthosilicate (the weight ratio of SiO2 to EMT in tetraethyl orthosilicate was 1.9:10) was added to the crystallization solution, and the mixture was stirred at room temperature for 12 hours. Finally, 7.6 g of tetrapropylammonium hydroxide (TPAOH, 25%) was added to obtain a dispersion. The dispersion was crystallized at 80℃ for 3 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 core-shell structured EMT molecular sieve S2 with a surface silicon-to-aluminum ratio of 26.0. The estimated surface silicon crystalline phase layer coverage was 95.7%. Incremental calculations showed that the weight of the surface silicon crystalline layer accounted for 7 wt% of the total weight of the modified molecular sieve.

[0084] The core-shell structured EMT molecular sieve S2 and alumina were shaped and calcined according to a formulation of 80 wt% and 20 wt% by weight (dry basis) to obtain the deolefination catalyst S2.

[0085] Five g of the above-mentioned deolefination catalyst S2 was used to conduct a non-hydrogenated deolefination experiment in a fixed-bed reactor. The feedstock was the bottom product of a heptane removal tower containing 80 mg / 100 ml of gum, with a bromine index of 1600 mgBr / 100 g oil. The reaction temperature was 170 °C, the reaction pressure was 2.0 MPa, and the weight hourly space velocity (WHSV) was 10.0 h⁻¹. -1 After 240 hours of reaction, the reactor outlet had a gum content of 77 mg / 100 ml and an outlet bromine index of 260 mgBr / 100 g oil.

[0086]

Example 3

[0087] Sodium aluminate, sodium phosphate, and sodium hydroxide (calculated as Na2O) were dissolved in distilled water to obtain solution i. Silica (calculated as SiO2), 18-crown ether-6, and water were mixed and stirred until homogeneous 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 = 1:10:2.1:0.05:0.66:200. The mixture was crystallized at 110℃ for 3 days to obtain a crystallized solution. After filtration, washing, drying, and calcination, 37 grams of EMT molecular sieve (dry basis) with a surface silicon-to-aluminum ratio of 4.3 was obtained.

[0088] The above process was repeated to obtain an EMT molecular sieve crystallization solution. 17 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, 4 g of tetrapropylammonium hydroxide (TPAOH, 25%) was added to obtain a dispersion. The dispersion was crystallized at 90℃ for 2 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 core-shell structured EMT molecular sieve S3 with a surface silicon-to-aluminum ratio of 11.1. The estimated surface silicon crystalline phase layer coverage was 87.1%. The incremental calculation results showed that the weight of the surface silicon crystalline layer accounted for 2 wt% of the total weight of the modified molecular sieve.

[0089] The core-shell structured EMT molecular sieve S3 and alumina were shaped and calcined according to a formulation of 80 wt% and 20 wt% by weight (dry basis) to obtain the deolefination catalyst S3.

[0090] Five g of the above-mentioned deolefination catalyst S3 was used to conduct a non-hydrogenated deolefination experiment in a fixed-bed reactor. The feedstock was the bottom product of a heptane removal tower containing 80 mg / 100 ml of gum, with a bromine index of 1600 mgBr / 100 g oil. The reaction temperature was 170 °C, the reaction pressure was 2.0 MPa, and the weight hourly space velocity (WHSV) was 10.0 h⁻¹. -1 After 240 hours of reaction, the reactor outlet had a gum content of 69 mg / 100 ml and an outlet bromine index of 530 mgBr / 100 g oil.

[0091]

Example 4

[0092] Aluminum sulfate octahydrate, sodium phosphate, and sodium hydroxide (calculated as Na2O) were dissolved in distilled water to obtain solution i. Silica sol (SiO2 weight percentage 40%), 18-crown ether-6, and water were mixed and stirred until homogeneous 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 = 1:10.9:1.7:0.05:0.33:170. The mixture was crystallized at 100℃ for 4 days to obtain a crystallized solution. After filtration, washing, drying, and calcination, 35 g of EMT molecular sieve (dry basis) was obtained, with a surface silicon-to-aluminum ratio of 3.9.

[0093] The above process was repeated to obtain an EMT molecular sieve crystallization solution. 21 g of tetraethyl orthosilicate (the weight ratio of SiO2 to EMT in tetraethyl orthosilicate was 1.7:10) was added to the crystallization solution, and the mixture was stirred at room temperature for 12 hours. Finally, 8.5 g of tetrapropylammonium hydroxide (TPAOH, 25%) was added to obtain a dispersion. The dispersion was crystallized at 80℃ for 3 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 core-shell structured EMT molecular sieve S4. The surface silicon-to-aluminum ratio was 11.7, and the estimated surface silicon crystalline phase layer coverage was 88.7%. Incremental calculations showed that the weight of the surface silicon crystalline layer accounted for 3 wt% of the total weight of the modified molecular sieve.

[0094] The core-shell structured EMT molecular sieve S4 and alumina were shaped and calcined according to a formulation of 80 wt% and 20 wt% by weight (dry basis) to obtain the deolefination catalyst S4.

[0095] Five g of the above-mentioned deolefination catalyst S4 was used in a non-hydrogenated deolefination experiment in a fixed-bed reactor. The feedstock was the bottom product of a heptane removal tower containing 80 mg / 100 ml of gum, with a bromine index of 1600 mgBr / 100 g oil. The reaction temperature was 170 °C, the reaction pressure was 2.0 MPa, and the weight hourly space velocity (WHSV) was 10.0 h⁻¹. -1 After 240 hours of reaction, the reactor outlet had a gum content of 72 mg / 100 ml and an outlet bromine index of 470 mgBr / 100 g oil.

[0096]

Example 5

[0097] Aluminum sulfate octahydrate, sodium phosphate, and sodium hydroxide (calculated as Na2O) were dissolved in distilled water to obtain solution i. Silica (calculated as SiO2), 18-crown ether-6, and water were mixed and stirred until homogeneous 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 = 1:10.9:1.7:0.05:0.66:170. The mixture was crystallized at 100℃ for 3 days to obtain a crystallization solution. The solution was filtered to obtain an EMT molecular sieve filter cake. 60 grams of water were added to the EMT molecular sieve filter cake. After thorough mixing, 20 g of tetraethyl orthosilicate (with a SiO2 to EMT weight ratio of 1.6:10 in the tetraethyl orthosilicate) was added and stirred at room temperature for 12 hours. Finally, 5 g of tetrapropylammonium hydroxide (TPAOH, 25%) was added to obtain a dispersion. The dispersion was crystallized at 80℃ for 3 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 core-shell structured EMT molecular sieve S5. The surface silicon-to-aluminum ratio was 10.7, and the estimated surface silicon crystalline phase layer coverage was 86.8%. The incremental calculation results showed that the weight of the surface silicon crystalline layer accounted for 2 wt% of the total weight of the modified molecular sieve.

[0098] The core-shell structured EMT molecular sieve S5 and alumina were molded and calcined according to a formula of 80 wt% and 20 wt% by weight (dry basis) to obtain the deolefination catalyst S5.

[0099] Five g of the above-mentioned deolefination catalyst S5 was used to conduct a non-hydrogenated deolefination experiment in a fixed-bed reactor. The feedstock was the bottom product of a heptane removal tower containing 80 mg / 100 ml of gum, with a bromine index of 1600 mgBr / 100 g oil. The reaction temperature was 170 °C, the reaction pressure was 2.0 MPa, and the weight hourly space velocity (WHSV) was 10.0 h⁻¹. -1 After 240 hours of reaction, the amount of colloid at the reactor outlet was 63 mg / 100 ml (the silicon crystal phase layer had low coverage, and the colloid was adsorbed on the EMT), and the bromine index at the outlet was 590 mgBr / 100 g oil.

[0100]

Example 6

[0101] Five g of the deolefination catalyst S1 prepared in Example 1 was used in a non-hydrogenated deolefination experiment in a fixed-bed reactor. The feedstock was the bottom product of a heptane degassing column containing 150 mg / 100 ml of gum, with a bromine index of 2100 mgBr / 100 g oil. The reaction temperature was 220 °C, the reaction pressure was 2.5 MPa, and the weight hourly space velocity was 5.0. -1 After 240 hours of reaction, the reactor outlet had 126 mg / 100 ml of gum and an outlet bromine index of 330 mgBr / 100 g oil.

[0102]

Example 7

[0103] Five g of the deolefination catalyst S2 prepared in Example 2 was used in a non-hydrogenated deolefination experiment in a fixed-bed reactor. The feedstock was the bottom product of a heptane degassing column containing 50 mg / 100 ml of gum, with a bromine index of 900 mgBr / 100 g oil. The reaction temperature was 150 °C, the reaction pressure was 1.0 MPa, and the weight hourly space velocity (WHSV) was 15.0 h⁻¹. -1 After 240 hours of reaction, the reactor outlet had 44 mg / 100 ml of gum and an outlet bromine index of 210 mgBr / 100 g oil.

[0104] Comparative Example 1

[0105] The preparation process of EMT molecular sieve is the same as in Example 1.

[0106] 33.3 g of aluminum sulfate octahydrate, 0.95 g of sodium phosphate, and 6.8 g of sodium hydroxide were dissolved in 68 g of distilled water to obtain solution i. 32.7 g of silica, 8.7 g of 18-crown ether-6, and 69 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 = 1:10.9:1.7:0.05:0.66:170. The mixture was crystallized at 100℃ 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℃ and calcined at 550℃ for 3 hours to obtain EMT molecular sieve D1.

[0107] EMT molecular sieve D1 and alumina were shaped and calcined according to a formulation of 80 wt% and 20 wt% by weight (dry basis) to obtain deolefin catalyst D1.

[0108] Five g of the above-mentioned deolefination catalyst D1 was used in a non-hydrogenated deolefination experiment in a fixed-bed reactor. The feedstock was the bottom product of a heptane removal tower containing 80 mg / 100 ml of gum, with a bromine index of 1600 mgBr / 100 g oil. The reaction temperature was 170 °C, the reaction pressure was 2.0 MPa, and the weight hourly space velocity (WHSV) was 10.0 h⁻¹. -1 After 240 hours of reaction, the amount of gum at the reactor outlet was 18 mg / 100 ml, and the bromine index at the outlet was 1380 mgBr / 100 g oil, indicating that the catalyst had been deactivated and most of the gum had entered the catalyst channels.

[0109] Comparative Example 2

[0110] 20 g of tetraethyl orthosilicate was added to the EMT molecular sieve filter cake obtained in Example 5 for equal-volume impregnation, dried at 120 °C, and calcined at 550 °C for 3 hours to obtain modified EMT molecular sieve D2. The surface silica-to-alumina ratio was 53.0, and the estimated surface silica coverage was 98%. The incremental calculation results showed that the surface silica accounted for 10.7 wt% of the total weight of the modified molecular sieve.

[0111] Catalyst D2 for reducing the bromine index of aromatic feedstock was obtained by molding and calcining D2 and alumina according to a formulation of 80wt% and 20wt% by weight (dry basis).

[0112] Five g of the above-mentioned deolefination catalyst D2 was used to conduct a non-hydrogenated deolefination experiment in a fixed-bed reactor. The feedstock was the bottom product of a heptane removal tower containing 80 mg / 100 ml of gum, with a bromine index of 1600 mgBr / 100 g oil. The reaction temperature was 170 °C, the reaction pressure was 2.0 MPa, and the weight hourly space velocity (WHSV) was 10.0 h⁻¹. -1 After 240 hours of reaction, the amount of gum at the reactor outlet was 76 mg / 100 ml, and the bromine index at the outlet was 1430 mgBr / 100 g oil, indicating that the catalyst had neither the ability to block gum nor the ability to remove olefins.

[0113] Comparative Example 3

[0114] The EMT molecular sieve filter cake obtained in Example 1 was dried at 100°C for 12 hours and then calcined at 550°C for 3 hours before being pulverized.

[0115] 120g of water was added to the EMT molecular sieve powder, stirred, and then 20g of tetraethyl orthosilicate (the weight ratio of SiO2 to EMT in tetraethyl orthosilicate was 1.6:10). The mixture was stirred at room temperature for 12 hours, and finally 5g of tetrapropylammonium hydroxide (TPAOH, 25%) was added to obtain a dispersion. The dispersion was crystallized at 80℃ for 3 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 core-shell structured EMT molecular sieve D3 with a surface silicon-to-aluminum ratio of 4.8. The estimated surface silicon crystalline phase layer coverage was 42.7%. The incremental method calculation results showed that the weight of the surface silicon crystalline layer accounted for 1.5wt% of the total weight of the modified molecular sieve.

[0116] The core-shell structured EMT molecular sieve D3 and alumina were shaped and calcined according to a formulation of 80 wt% and 20 wt% by weight (dry basis) to obtain the deolefination catalyst D3.

[0117] Five g of the above-mentioned deolefination catalyst D3 was used in a non-hydrogenated deolefination experiment in a fixed-bed reactor. The feedstock was the bottom product of a heptane removal tower containing 80 mg / 100 ml of gum, with a bromine index of 1600 mgBr / 100 g oil. The reaction temperature was 170 °C, the reaction pressure was 2.0 MPa, and the weight hourly space velocity (WHSV) was 10.0 h⁻¹. -1 After 240 hours of reaction, the reactor outlet had a gum content of 33 mg / 100 ml and an outlet bromine index of 970 mgBr / 100 g oil.

[0118] 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 process for the removal of olefins from a gummy-containing aromatic hydrocarbon, comprising: The gummy aromatic hydrocarbon is contacted with a catalyst for deolefination, wherein the catalyst comprises a core-shell structure EMT molecular sieve; the core-shell structure EMT molecular sieve comprises an EMT molecular sieve core and a silicon crystal phase layer shell, and in the core-shell structure EMT molecular sieve, the silicon crystal phase layer shell accounts for 1-20 wt%, the coverage of the silicon crystal phase layer shell is greater than 85%, and the silicon crystal phase layer on the EMT surface is a high-silicon or pure-silicon molecular sieve with an MFI structure; the deolefination conditions include a temperature of 150-270 DEG C, a pressure of 0.6-3.0 MPa, and a weight hourly space velocity of the gummy aromatic hydrocarbon of 2-25 h -1 .

2. The method of claim 1, wherein, The catalyst further comprises a binder.

3. The method of claim 1, wherein, the gum content of the gum-containing aromatic hydrocarbon is 30-200 mg / 100 ml; and / or, the aromatic hydrocarbon in the gum-containing aromatic hydrocarbon is C8 and above aromatic hydrocarbon.

4. The method of claim 1, wherein, the gum content of the gum-containing aromatic hydrocarbon is 50-150 mg / 100 ml; and / or, the gum-containing aromatic hydrocarbon is from a catalytic reforming unit in an aromatic hydrocarbon complex.

5. The method of claim 4, wherein, the gum-containing aromatic hydrocarbon is a deheptanizer column bottom liquid in the catalytic reforming unit.

6. The method of claim 1, wherein, temperature is 150 to 220°C, and / or, the pressure is 1 to 2.5 MPa, and / or, the weight hourly space velocity of the gummy aromatic hydrocarbon is 5 to 15 h -1 .

7. The method of claim 2, wherein, the binder is selected from at least one of alumina, aluminum sol, silica sol, and clay.

8. The method of claim 2, wherein, the content of the binder is 20-40 wt% based on 100 wt% of the total weight of the catalyst, and the content of the core-shell structure EMT molecular sieve is 60-80 wt%.

9. The method of claim 1, wherein, in the core-shell structure EMT molecular sieve, the proportion of the silicon crystal phase layer shell is 2-10 wt%.

10. The method according to one of claims 1 to 9, characterized in that the core-shell structure EMT molecular sieve is prepared as follows: (1) obtaining an EMT molecular sieve, or subjecting a dispersion liquid A containing an aluminum source, a silicon source A, sodium hydroxide, a template agent A, a solvent, and an auxiliary agent to crystallization treatment to obtain an EMT molecular sieve crystallization liquid; (2) mixing the EMT molecular sieve or the EMT molecular sieve crystallization liquid with a silicon source B, a template agent B, and a dispersant to obtain a dispersion liquid B; (3) subjecting the dispersion liquid B to crystallization treatment, and then subjecting to post-treatment to obtain the core-shell structure EMT molecular sieve.

11. The method of claim 10, wherein, in step (1), the aluminum source is selected from at least one of sodium metaaluminate, aluminum nitrate, aluminum sulfate, aluminum sol, and pseudo-boehmite; and / or, in step (1), the silicon source A is selected from at least one of sodium silicate, silica sol, white carbon black, and water glass; and / or, in step (1), the molar ratio of the silicon source A to the aluminum source is (8-11):1, wherein the molar amount of the silicon source A is calculated based on the molar amount of SiO2 therein, and the molar amount of the aluminum source is calculated based on the molar amount of Al2O3 therein.

12. The method of claim 11, wherein, in step (1), the molar ratio of the silicon source A to the aluminum source is (10-11):1, wherein the molar amount of the silicon source A is calculated based on the molar amount of SiO2 therein, and the molar amount of the aluminum source is calculated based on the molar amount of Al2O3 therein.

13. The method of claim 10, wherein, in step (1), the template agent A is 18-crown-6.

14. The method of claim 10, wherein, the molar ratio of the template agent A to the aluminum source is (0.2-1):1, wherein the molar amount of the template agent A is calculated based on the molar amount of its molecule, and the molar amount of the aluminum source is calculated based on the molar amount of Al2O3 therein.

15. The method of claim 10, wherein, the molar ratio of the template agent A to the aluminum source is (0.33-0.7):1, wherein the molar amount of the template agent A is calculated based on the molar amount of its molecule, and the molar amount of the aluminum source is calculated based on the molar amount of Al2O3 therein.

16. The method of claim 10, wherein, in step (1), the solvent is water; and / or, in step (1), the auxiliary agent is selected from inorganic salt emulsifiers and / or, In step (1), the molar ratio of sodium hydroxide to the aluminum source is (1-3):1, wherein the molar amount of sodium hydroxide is calculated based on the molar amount of Na2O, and the molar amount of the aluminum source is calculated based on the molar amount of Al2O3 in the aluminum source.

17. The method of claim 10, wherein, In step (1), the molar ratio of the solvent to the aluminum source is (100-400):1, wherein the molar amount of the solvent is calculated based on the molar amount of the molecule of the solvent, and the molar amount of the aluminum source is calculated based on the molar amount of Al2O3 in the aluminum source. and / or, In step (1), the auxiliary agent is selected from at least one of sodium phosphate, sodium diphosphate, and sodium triphosphate. and / or, In step (1), the molar ratio of sodium hydroxide to the aluminum source is (1.5-2.5):1, wherein the molar amount of sodium hydroxide is calculated based on the molar amount of Na2O, and the molar amount of the aluminum source is calculated based on the molar amount of Al2O3 in the aluminum source.

18. The method of claim 10, wherein, In step (1), the molar ratio of the solvent to the aluminum source is (120-200):1, wherein the molar amount of the solvent is calculated based on the molar amount of the molecule of the solvent, and the molar amount of the aluminum source is calculated based on the molar amount of Al2O3 in the aluminum source. and / or, In step (1), the molar ratio of the auxiliary agent to the aluminum source is (0.02-0.1):1, wherein the molar amount of the auxiliary agent is calculated based on the molar amount of Na3PO4, and the molar amount of the aluminum source is calculated based on the molar amount of Al2O3 in the aluminum source.

19. The method of claim 10, wherein, In step (1), the temperature of the crystallization treatment is 80-130°C; and / or, the time of the crystallization treatment is 0.5-5d.

20. The method of claim 10, wherein, In step (1), the temperature of the crystallization treatment is 90-110°C; and / or, the time of the crystallization treatment is 2-3d.

21. The method of claim 10, wherein, In step (2), the EMT molecular sieve or the solution containing the EMT molecular sieve is first mixed with the silicon source B and stirred, and then the template B and the dispersant are added to obtain the dispersion B.

22. The method of claim 10, wherein, In step (2), the silicon source B is selected from silica sol and / or silicate; and / or, In step (2), the weight ratio of the silicon source B to the EMT molecular sieve is (0.5-4):10, wherein the weight of the silicon source B is calculated based on the SiO2 content; and / or, In step (2), the template B is selected from at least one of tetrapropylammonium bromide and tetrapropylammonium hydroxide; and / or, In step (2), the dispersant is water.

23. The method of claim 22, wherein, In step (2), the silicate is alkyl orthosilicate; and / or, In step (2), the weight ratio of the silicon source B to the EMT molecular sieve is (1-2):10, wherein the weight of the silicon source B is calculated based on the SiO2 content; and / or, In step (2), the weight ratio of the template B to the silicon source B is (1-5):10, wherein the weight of the template B is calculated based on the dry basis, and the weight of the silicon source B is calculated based on the SiO2 content.

24. The method of claim 22, wherein, in step (2), the silicon source B is at least one selected from the group consisting of silica sol, tetramethyl orthosilicate, tetraethyl orthosilicate, tetrapropyl orthosilicate, and tetrabutyl orthosilicate; and / or, in step (2), the weight ratio of the template B to the silicon source B is (2-4): 10, wherein the weight of the template B is on a dry basis and the weight of the silicon source B is on an SiO2 content basis.

25. The method of claim 10, wherein, in step (3), the temperature of the crystallization treatment is 70-90°C; and / or, in step (3), the post-treatment includes suction filtration, water washing, drying, and calcination.