A method for selectively removing olefin impurities from reformate

Abstract

The application discloses a method for selectively removing olefin impurities in aromatic hydrocarbons. The method is provided with at least two olefin removal reactors, namely an olefin removal reactor I and an olefin removal reactor II, and the process comprises the following steps: (1) reforming generated oil is introduced into the olefin removal reactor I to react with an olefin removal catalyst; (2) the reaction product obtained in the step (1) is introduced into a xylene fraction column to be fractionated, and mixed xylene is obtained at the top of the column; wherein when the content of olefin in the mixed xylene obtained in the step (2) reaches 10-50 ppm, the reforming generated oil is switched to the olefin removal reactor II to perform an olefin removal reaction, and the mixed xylene obtained in the step (2) is used as the feed of the olefin removal reactor I to regenerate the olefin removal catalyst therein. The method can selectively remove the olefin impurities in the reforming generated oil, and can greatly prolong the operation cycle of the device.

Description

Technical Field

[0001] This invention relates to the field of aromatics production, and more specifically, to a method for selectively removing olefin impurities from reforming products. Background Technology

[0002] In the production of aromatics, aromatics generated by reforming or other reactions generally contain small amounts of olefins, which must be removed before becoming the final product. This is especially true for olefins in C8 aromatic components and components with lower boiling points that affect product quality (such as toluene and para-xylene). The presence of olefin impurities in aromatics leads to two main problems: first, it reduces the quality of aromatic products, affecting aspects such as color, purity, and stability; second, in the industrial production of para-xylene, olefins come into contact with adsorbents or catalysts in adsorption separation units and disproportionation units, reducing their efficiency and lifespan.

[0003] Currently, two technical routes are used industrially to remove olefins from reformed aromatics: hydrogenation and liquid-phase non-hydrogenation reaction. Hydrogenation involves large investments in equipment, complex modifications, high operating costs, significant aromatic loss, and expensive catalysts. As it is the reverse reaction of reforming, it impacts the material consumption and scale of the plant. Liquid-phase non-hydrogenation reaction, on the other hand, requires less investment, is easier to operate, and results in less aromatic loss, making it more suitable for industrial applications.

[0004] In practical applications, non-hydrogen-dependent liquid-phase deolefin removal technology for aromatics typically uses clay or molecular sieves as catalysts. Olefins undergo alkylation reactions with aromatics, thereby removing the olefins. The types of olefins mainly include those with seven or fewer carbon atoms, eight carbon atoms, and nine or more carbon atoms. Among these, the olefins affecting p-xylene products are primarily those with eight or fewer carbon atoms, and existing catalysts cannot effectively and selectively remove these olefins. Current reaction processes directly employ reforming to generate an oil-liquid phase reaction. The diffusion rate of the resulting large molecular products is much lower than the gas-phase diffusion rate. If the residence time within the catalyst is too long, it can easily lead to further reactions, generating excessively large polycyclic aromatic polymers, causing gradual catalyst deactivation. Molecular sieve catalysts have a longer service life than clay catalysts, and can be regenerated after deactivation for continued use. However, the regeneration technology for molecular sieve catalysts is not perfect. Methods such as shutting down the plant, unloading the catalyst, and then coking for removal, or in-situ regeneration, often result in significant performance degradation after regeneration.

[0005] US patents US4202865 and US4780195 disclose the use of oxygen to burn coke to regenerate catalysts. Chinese patent CN102151589A discloses a method of regenerating deactivated catalysts by purging them with nitrogen, steam, etc. to remove reactants, rinsing them with a mixed solution of peroxide, alcohol, etc., and finally purging them with steam, nitrogen, etc.

[0006] Therefore, there is an urgent need to develop a method that can extend the operating cycle of the equipment and selectively remove olefins from xylene products. Summary of the Invention

[0007] To address the problems of low olefin removal selectivity, poor activity stability, and frequent shutdowns for regeneration in existing non-hydrogenated olefin removal catalysts for aromatics, this invention provides a novel method for selectively removing olefin impurities from reformate. This method can achieve highly selective removal of olefin impurities from reformate and significantly extend the operating cycle of the unit.

[0008] The first aspect of this invention provides a method for selectively removing olefin impurities from aromatic hydrocarbons, wherein at least two deolefin reactors, namely deolefin reactor I and deolefin reactor II, are provided, and the method includes:

[0009] (1) The reformed oil enters the deolefin reactor I and reacts with the deolefin catalyst;

[0010] (2) The reaction product obtained in step (1) enters the xylene fractionation tower for fractionation, and mixed xylene is obtained at the top of the tower; wherein, when the olefin mass content in the mixed xylene obtained in step (2) reaches 10-50 ppm, the reforming oil feed is switched to the deolefin reactor II for deolefin reaction, and the mixed xylene obtained in step (2) is used as the feed of the deolefin reactor I for regenerating the deolefin catalyst therein.

[0011] Further, preferably, when the olefin content in the mixed xylene obtained in step (2) reaches 10-50 ppm, the mixed xylene obtained in step (2) is added as another feed to the deolefin reactor I. Then, when the olefin content in the mixed xylene obtained in step (2) reaches 10-20 ppm, the reforming oil feed is switched to the deolefin reactor II for deolefin reaction. The mixed xylene obtained in step (2) is used as feed to the deolefin reactor I to regenerate the deolefin catalyst therein.

[0012] Furthermore, the olefin content in the reformed oil, calculated by the bromine index, is 200–2800 mgBr / 100g.

[0013] Furthermore, the deolefin reactor I or deolefin reactor II is a fixed-bed reactor, which is filled with a deolefin catalyst. The deolefin catalyst is clay or a molecular sieve catalyst, preferably a molecular sieve catalyst containing a twelve-membered ring. The molecular sieve is at least one or more of Y, β, MCM-22, MCM-56, SAPO-5, SAPO-37, and SAPO-40.

[0014] Further, preferably, the molecular sieve catalyst comprises, by weight, the following components:

[0015] a) 50-90 parts of molecular sieves containing twelve-membered rings or more;

[0016] b) 0.1 to 10 parts of the additive component, calculated as oxide; the additive component is selected from at least one of Group IA and Group IIA;

[0017] c) 0.1 to 10 parts of the modifying component, calculated as oxide; the modifying component is selected from at least one of silicon, germanium, bismuth, tin and boron;

[0018] d) 10 to 49 parts of adhesive components.

[0019] Further, in component a), the molecular sieve is selected from at least one of molecular sieves such as Y (e.g., USY), β, MCM-22, MCM-56, SAPO-5, SAPO-37, and SAPO-40. Preferably, the molecular sieve is selected from at least one of Y, β, MCM-56, and MCM-22. More preferably, the SiO2 / Al2O3 molar ratio of the molecular sieve is 2 to 60.

[0020] Further, in component d), the binder component is derived from at least one of alumina, kaolin, attapulgite, bentonite, diatomaceous earth, and silica, preferably alumina.

[0021] Further, in component b), the added component is selected from at least one of Group IA (e.g., potassium, sodium) and Group IIA (e.g., calcium, magnesium), preferably magnesium.

[0022] Further, in component c), the modified component is selected from silicon and at least one selected from germanium, bismuth, tin and boron, preferably silicon and at least one selected from tin, bismuth and germanium, more preferably silicon and tin, wherein the mass ratio of silicon as silicon oxide to at least one selected from tin, bismuth, germanium and boron as oxide is 0.1 to 10.0, preferably 1.5 to 5.0.

[0023] Furthermore, the molecular sieve is preferably 55 to 80 parts by weight.

[0024] Furthermore, the adhesive component is preferably 15 to 40 parts by weight.

[0025] Further, the added component is preferably 1.0 to 8.0 parts by weight.

[0026] Further, the modified component is preferably 1.0 to 8.0 parts by weight.

[0027] Furthermore, the pore distribution of the molecular sieve of component a) is as follows: the pore volume occupied by pores with a diameter of 0.5 to 2.0 nm accounts for 5% to 40% of the total pore volume, and the pore volume occupied by pores with a diameter of 2 to 50 nm accounts for 20% to 50% of the total pore volume.

[0028] Furthermore, the preparation method of the above-mentioned molecular sieve catalyst includes:

[0029] (11) Mix molecular sieve, binder, additive precursor, mold, dry and calcinate to obtain molded body;

[0030] (12) The modified component precursor is loaded onto the molded body, and then dried and calcined to obtain the catalyst.

[0031] Further, the binder mentioned in step (11) is selected from at least one of alumina, kaolin, attapulgite, bentonite, diatomaceous earth, and silica, preferably alumina. The precursor of the added component can be nitrate, chloride, etc. The molding can be a conventional molding method, such as extrusion molding, sheet molding, etc. Depending on the molding requirements, molding aids are usually added, such as at least one of nitric acid, extrusion aid (such as guar gum), and water.

[0032] Further, the drying conditions described in step (11) are as follows: drying temperature 30–300℃, drying time 0.5–72h; the calcination conditions are as follows: calcination temperature 450–700℃, calcination time 0.2–30h. The drying and calcination are carried out in an oxygen-containing atmosphere (such as air, oxygen).

[0033] Further, in the modified component precursor described in step (12), the silicon precursor is preferably an organosilicon, such as tetraethyl orthosilicate, silicone oil (preferably selected from at least one of phenylmethyl silicone oil, amino silicone oil, and hydroxyl silicone oil), methyl silicate, siloxane (alkyl group with 1-4 carbon atoms) monomer, and at least one of halosiloxane (alkyl group with 1-4 carbon atoms, such as chlorosilane). The precursors for germanium, bismuth, and tin can be soluble salts, such as nitrates, chlorides, and sulfates, while the precursor for boron can be boric acid, etc.

[0034] Further, the preferred process of step (12) is as follows: first, silicon is impregnated onto the molded body, and then at least one selected from germanium, bismuth, tin, and boron is impregnated onto it. Further, the specific process is as follows: the molded body is impregnated with an organosilicon-containing impregnation solution, dried to obtain a silicon-containing molded body, and then impregnated with an impregnation solution containing at least one selected from germanium, bismuth, tin, and boron, dried and calcined to obtain the catalyst. The solvent used in the organosilicon-containing impregnation solution is at least one selected from toluene and alkanes (with 5-16 carbon atoms). The impregnation is preferably performed using an equal-volume impregnation method. The drying conditions for preparing the silicon-containing molded body are as follows: drying temperature 30–200°C, drying time 0.1–72 h, and the drying is carried out under an inert atmosphere (e.g., nitrogen).

[0035] Further, the drying conditions in step (12) are as follows: drying temperature 30–200℃, drying time 0.1–72h; the calcination conditions are as follows: calcination temperature 400–650℃, calcination time 0.5–8h. The drying and calcination are carried out under an inert atmosphere (such as nitrogen).

[0036] Further, the reaction conditions for the reaction described in step (1) are as follows: temperature 140-230℃, pressure 0.3-5.0 MPa, and liquid hourly space velocity 0.2-20 h⁻¹. -1 .

[0037] Furthermore, the operating conditions of the xylene fractionation column in step (2) are as follows: the top temperature is 200-250℃, the bottom temperature is 230-295℃, and the pressure is 0.4-1.2MPa.

[0038] Furthermore, when the olefin content in the mixed xylene obtained in step (2) reaches 10-50 ppm, the reforming oil feed is switched to the deolefin reactor II for deolefin reaction. When the mixed xylene obtained in step (2) is used as feed to the deolefin reactor I for regenerating the deolefin catalyst therein, the operating conditions of the deolefin reactor I are as follows: temperature 200-230℃, pressure 0.5-5.0 MPa, and liquid hourly space velocity 0.2-5.0 h⁻¹. -1 The regeneration time is 1-300 hours.

[0039] Furthermore, after the deolefin catalyst in the deolefin reactor I is regenerated, the feed is switched to reformate oil for the deolefin reaction in step (1).

[0040] Furthermore, when the olefin content in the mixed xylene obtained in step (2) reaches 10-50 ppm, when the mixed xylene obtained in step (2) is added as another feed to the deolefin reactor I (i.e., the reforming oil and the mixed xylene obtained in step (2) are simultaneously used as feed to the deolefin reactor I), the feed ratio of the mixed xylene obtained in step (2) to the feed mass of the reforming oil is 0.01-1.0, preferably 0.1-0.5, and the feed temperature of the mixed xylene obtained in step (2) is 180-240℃. Preferably, the feed temperature of the mixed xylene is at least 10℃ higher than the feed temperature of the reforming oil. Subsequently, when the olefin content in the mixed xylenes obtained in step (2) reaches 10-20 ppm, the reforming oil feed is switched to deolefin reactor II for deolefin reaction. When the mixed xylenes obtained in step (2) is used as feed to deolefin reactor I for regenerating the deolefin catalyst therein, the operating conditions of deolefin reactor I are as follows: temperature 200-230℃, pressure 0.5-5.0 MPa, and liquid hourly space velocity 0.2-5.0 h⁻¹. -1 The regeneration time is 1-300h. After the deolefin catalyst in the deolefin reactor I is regenerated, the feed is switched to reformate oil for the deolefin reaction in step (1).

[0041] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0042] 1. The inventors discovered through research that in the reforming-to-oil deolefins process, when the olefin content in the product does not meet the requirements, it is generally necessary to shut down the plant for in-situ or ex-situ regeneration of the deolefins catalyst before restarting production. This not only results in a short plant operating cycle but also requires separate start-up and shutdown times. Further research by the inventors revealed that the mixed xylene material produced in the reforming-to-oil deolefins process can achieve online in-situ regeneration of the deolefins catalyst. This not only saves start-up and shutdown time but also ensures that the regenerated deolefins catalyst exhibits good performance recovery, thus extending the plant's operating cycle.

[0043] 2. The method of the present invention uses a preferred deolefination catalyst, which is a combination of molecular sieves with specific pore distribution, additive components, and modifying components, so that the catalyst has high deolefination activity while ensuring a long lifespan.

[0044] 3. The method of the present invention uses a preferred deolefin catalyst. In the preparation method of the catalyst, the additive components are first mixed with molecular sieves and shaped, and then the modified components are loaded. Moreover, the modified components are preferably first impregnated and loaded onto the shaped body with an impregnation liquid containing organosilicon, and then other modified components are impregnated and loaded. This is beneficial to further prevent the polymerization of olefin compounds, delay the rate of catalyst coking and deactivation, and effectively extend the single-pass life of the catalyst. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the process flow of a method for selectively removing olefin impurities from aromatic hydrocarbons according to the present invention;

[0046] The reference numerals in the attached diagram are explained as follows: 1-Reformed oil, 2-Reformed oil after heat exchange, 3-Materials after olefin impurities have been removed by the deolefin reactors C1 and / or C2, 4-Bottom material of the xylene tower, 5-Mixed xylene material refluxed to the xylene tower, 6-Mixed xylene material obtained from the top of the xylene tower after separation, 7-Mixed xylene product, 8-Mixed xylene material from the top of the xylene tower before entering the deolefin reactor; a-Fracturing tower, b-Xylene tower, C1-Deolefin reactor, C2-Deolefin reactor. Detailed Implementation

[0047] The present invention will be further illustrated below through examples:

[0048] This invention provides a process flow diagram of a method for selectively removing olefin impurities from aromatic hydrocarbons (e.g.) Figure 1 The method of this invention includes: reforming oil 1 obtained from the bottom of fractionation tower a is heated by a heat exchanger to obtain reforming oil 2, which is then fed into a de-olefin reactor C1 to react with a de-olefin catalyst. The resulting reaction product 3 is fed into a xylene fractionation tower b for fractionation. A portion of the mixed xylene material 5 is refluxed back to the xylene tower, and a portion of the mixed xylene material 7 is discharged as product. The bottom material 4 enters the downstream section, and mixed xylene 6 is obtained at the top of the tower. When the olefin content in the mixed xylene 6 obtained at the top of the xylene fractionation tower reaches 10-50 ppm, the reforming oil feed is switched from C1 to the de-olefin reactor C2 for de-olefin reaction. The recycled mixed xylene 8 is used as feed to the de-olefin reactor C1 to regenerate the de-olefin catalyst therein.

[0049] Further, preferably, when the olefin content in the mixed xylene 6 obtained from the top of the xylene fractionation tower reaches 10-50 ppm, it is used as another feed for the deolefin reactor C1. Then, when the olefin content in the obtained mixed xylene 6 reaches 10-20 ppm, the reforming oil feed is switched from C1 to the deolefin reactor C2 for deolefin reaction, and the recycled mixed xylene 8 is used as the feed for the deolefin reactor C1 to regenerate the deolefin catalyst therein.

[0050] In this invention, pore volume and pore distribution were determined using a liquid nitrogen adsorption-desorption apparatus. The determination method is as follows: the test was conducted at the liquid nitrogen saturation temperature (77K), and N2 isothermal adsorption-desorption curves were obtained by different relative pressures. The pore volume and pore distribution were then calculated. The relative pressure during the experiment ranged from 0.001 to 0.995.

[0051] [Example 1]

[0052] Take 100g of USY molecular sieve (SiO2 / Al2O3 molar ratio of 12, pore distribution as follows: pore volume of 0.5-2.0nm accounts for 20% of the total pore volume, pore volume of 2-50nm accounts for 20% of the total pore volume), 65g of pseudoboehmite (containing 67wt% alumina), 12g of guar gum powder, 6g of 65wt% nitric acid, and magnesium nitrate aqueous solution, knead into a mold, dry at 120℃ for 12 hours in air atmosphere, and calcine at 580℃ for 2 hours to obtain the molded body. Then, 100g of the molded body was impregnated in 50g of an impregnation solution containing tetraethyl orthosilicate (toluene as solvent). After treatment under nitrogen at 70℃ for 3 hours, the solvent was removed, and the sample was dried at 120℃ for 10 hours. Next, 100g of the sample was impregnated with an equal volume of germanium chloride in an ethanol solution, with a silica to germanium oxide mass ratio of 5.0. The sample was dried at 120℃ for 5 hours under a nitrogen atmosphere and then calcined at 550℃ for 3 hours under a nitrogen atmosphere to obtain molecular sieve catalyst A. In the obtained molecular sieve catalyst A, the mass content of silica was 4.0%, the mass content of germanium oxide was 0.8%, and the mass content of magnesium oxide was 3.0%.

[0053] [Example 21]

[0054] Take 100g of Beta molecular sieve (SiO2 / Al2O3 molar ratio of 19, pore distribution as follows: pore volume of 0.5-2.0nm accounts for 35% of the total pore volume, and pore volume of 2-50nm accounts for 30% of the total pore volume), 40g of silica sol (containing 40wt% silicon oxide), add 12g of guar gum powder and magnesium nitrate aqueous solution, knead into a mold, dry at 120℃ for 12 hours in air atmosphere, and calcine at 550℃ for 2 hours to obtain the molded body. Then, 100g of the molded body was impregnated in 50g of an impregnation solution containing tetraethyl orthosilicate (ethanol as solvent). After treatment under nitrogen at 26℃ for 3 hours, the solvent was removed, and the sample was dried at 120℃ for 10 hours. Another 100g sample was then impregnated with an equal volume of an aqueous solution of tin sulfate, with a mass ratio of silica to tin oxide of 1.0. The sample was dried at 120℃ for 8 hours under a nitrogen atmosphere and calcined at 550℃ for 3 hours to obtain molecular sieve catalyst B. The obtained molecular sieve catalyst B contained 2.0% silica, 2.1% tin oxide, and 1.0% magnesium oxide.

[0055] [Example 3]

[0056] 100g of MCM-56 molecular sieve (SiO2 / Al2O3 molar ratio of 20, pore distribution as follows: pore volume of 0.5-2.0nm accounts for 20% of the total pore volume, and pore volume of 2-50nm accounts for 48% of the total pore volume) was mixed with 40g of silica sol (containing 40wt% silicon oxide), 12g of guar gum powder, and magnesium nitrate aqueous solution. The mixture was kneaded into a mold and dried at 120℃ for 12 hours in air, followed by calcination at 550℃ for 2 hours to obtain a shaped body. Then, 100g of the shaped body was impregnated in 50g of impregnation solution containing tetraethyl orthosilicate (ethanol as solvent), treated under nitrogen at 26℃ for 3 hours to remove the solvent, dried at 120℃ for 10 hours, and then 100g of the sample was impregnated with an equal volume of tin sulfate aqueous solution. The sample was dried at 120℃ for 8 hours in nitrogen atmosphere and then calcined at 550℃ for 3 hours to obtain molecular sieve catalyst C. The obtained molecular sieve catalyst C contains 5.4% silica by mass, 1.8% tin oxide by mass, and 7.5% magnesium oxide by mass.

[0057] [Example 41]

[0058] Take 100g of H-type MCM-22 molecular sieve (SiO2 / Al2O3 molar ratio of 15, pore distribution as follows: pore volume of 0.5-2.0nm accounts for 19% of the total pore volume, and pore volume of 2-50nm accounts for 45% of the total pore volume), 65g of pseudoboehmite (containing 67wt% alumina), 12g of guar gum powder, 6g of 65% nitric acid, and magnesium nitrate aqueous solution, knead into a mold, dry at 120℃ for 12 hours in air atmosphere, and calcine at 580℃ for 2 hours to obtain the molded body. Then, 100g of the molded body was impregnated in 50g of phenylmethyl silicone oil (toluene as solvent), treated at 70℃ under nitrogen for 3 hours to remove the solvent, and dried at 120℃ for 10 hours. Next, 100g of the sample was impregnated with an equal volume of tin sulfate aqueous solution, with a silica to tin oxide mass ratio of 2.0. Under a nitrogen atmosphere, it was dried at 120℃ for 5 hours and calcined at 550℃ for 3 hours to obtain molecular sieve catalyst D. The obtained molecular sieve catalyst D contained 3.6% silica, 1.8% tin oxide, and 2.1% magnesium oxide by mass.

[0059] [Example 5]

[0060] Take 100g of USY molecular sieve (SiO2 / Al2O3 molar ratio of 6, pore distribution as follows: pore volume of 0.5-2.0nm accounts for 22% of the total pore volume, and pore volume of 2-50nm accounts for 33% of the total pore volume), and 65g of pseudoboehmite (containing 67wt% alumina), add 12g of guar gum powder, an aqueous solution of sodium nitrate and magnesium nitrate, knead into a shape, dry at 120℃ for 12 hours in air atmosphere, and calcine at 580℃ for 2 hours to obtain the shaped body. Then, 100g of the molded body was impregnated in 50g of an impregnation solution containing amino silicone oil (heptane as solvent). After treatment under nitrogen at 26℃ for 3 hours, the solvent was removed, and the sample was dried at 120℃ for 10 hours. Another 100g sample was then impregnated with an equal volume of bismuth nitrate aqueous solution, with a mass ratio of silica to bismuth oxide of 10.0. The sample was dried at 120℃ for 8 hours under a nitrogen atmosphere and calcined at 650℃ for 3 hours to obtain molecular sieve catalyst E. The obtained molecular sieve catalyst E contains 7.0% silica, 0.7% bismuth oxide, 5.0% magnesium oxide, and 0.2% sodium oxide by mass.

[0061] [Example 6]

[0062] Take 100g of USY molecular sieve (SiO2 / Al2O3 molar ratio of 6, pore distribution as follows: pore volume of 0.5-2.0nm accounts for 21% of the total pore volume, and pore volume of 2-50nm accounts for 30% of the total pore volume), 30g of silica sol (containing 40wt% silicon oxide) and 20g of kaolin, add 12g of guar gum powder, an aqueous solution of sodium nitrate and calcium nitrate, knead into a shape, dry at 120℃ for 12 hours in air atmosphere, and calcine at 580℃ for 2 hours to obtain the shaped body. Then, 100g of the molded body was impregnated in 50g of an impregnation solution containing methyl silicone oil (heptane as solvent). After treatment under nitrogen at 26℃ for 3 hours, the solvent was removed, and the sample was dried at 120℃ for 10 hours. Another 100g sample was then impregnated with an equal volume of bismuth nitrate aqueous solution, with a mass ratio of silica to bismuth oxide of 10.0. The sample was dried at 120℃ for 8 hours under a nitrogen atmosphere and calcined at 550℃ for 3 hours to obtain molecular sieve catalyst F. The obtained molecular sieve catalyst F contained 6.0% silica, 0.6% bismuth oxide, 0.3% calcium oxide, and 1.2% sodium oxide.

[0063] [Example 71]

[0064] The operation process of this embodiment is as follows: Figure 1 As shown.

[0065] Reformed oil, with a mass content of 58.5% mixed xylene fraction, 36.8% C9 aromatic fraction, 4.4% C10 aromatic fraction and above, 0.1% toluene, 0.2% non-aromatics, and an olefin content of 1200 mgBr / 100g (based on bromine index), is heated in a heat exchanger and its temperature is controlled at 205℃, pressure at 1.0 MPa, and space velocity at 2.1 h⁻¹. 1 The product is fed into a deolefination reactor C1 containing catalyst A for reaction. The resulting product is then fed into a xylene fractionation column (top temperature 220℃, bottom temperature 282℃, pressure 1.0MPa) for separation. After 120 days of operation, a mixed xylene feedstock 6 with an olefin content of 15 mgBr / 100g (based on the bromine index) is separated at the top of the column. At this point, feedstock 2 is switched to a deolefination reactor C2 containing catalyst A (reactor C2 and reactor C1 use the same reactor and are loaded with the same amount of catalyst A) for reaction, while simultaneously controlling the temperature at 220℃ and the space velocity at 1.0 h⁻¹. 1 Mixed xylene feed 8, at a pressure of 1.0 MPa, enters reactor C1. The mixture 3 from the outlets of reactors C1 and C2 enters the xylene tower for separation. After 6 days of operation, feed 8 is stopped, and feed 2 is switched back to reactor C1 for deolefination. After processing in the xylene tower, the product, after a catalyst recycle of 110 days, yields mixed xylene feed 6 at the top of the tower with an olefin content (bromine index) of 15 mgBr / 100g. This process is repeated once more, resulting in a catalyst recycle of 106 days.

[0066] [Example 8]

[0067] The operation process of this embodiment is as follows: Figure 1 As shown.

[0068] Reformed oil, with a mass content of 58.5% mixed xylene fraction, 36.8% C9 aromatic fraction, 4.4% C10 aromatic fraction and above, 0.1% toluene, 0.2% non-aromatics, and an olefin content of 1200 mgBr / 100g (based on bromine index), is heated in a heat exchanger and maintained at a temperature of 202℃, a pressure of 1.0 MPa, and a space velocity of 1.5 h⁻¹. 1 The product is fed into a deolefination reactor C1 containing catalyst B for reaction. The resulting product is then fed into a xylene fractionation column (top temperature 220℃, bottom temperature 282℃, pressure 1.0 MPa) for separation. After 150 days of operation, a mixed xylene feedstock 6, with an olefin content (based on the bromine index) of 15 mgBr / 100 g, is separated at the top of the column. Feedstock 2 is then transferred to a deolefination reactor C2 containing catalyst B (reactor C2 uses the same reactor as reactor C1 and is loaded with the same amount of catalyst B) for further reaction, while maintaining a temperature of 220℃, a pressure of 1.0 MPa, and a space velocity of 1.0 h⁻¹. 1Mixed xylene feed 8 enters the de-olefin reactor C1 containing catalyst B. The mixture 3 from the outlets of reactors C1 and C2 enters the xylene tower for separation. After 10 days of operation, feed 8 is stopped, and feed 2 is switched back to reactor C1 for de-olefin reaction. After the product is processed by the xylene tower, the catalyst runs for another 140 days, and then mixed xylene feed 6 is separated from the top of the tower, with an olefin content of 15 mgBr / 100g based on the bromine index.

[0069] [Example 91]

[0070] The operation process of this embodiment is as follows: Figure 1 As shown in the figure. In order to speed up the experimental process, a catalyst deactivation test was conducted using increased space velocity.

[0071] The reformed oil, containing 50.5% mixed xylene fraction, 38.3% C9 aromatic fraction, 10.9% C10 aromatic fraction and above, 0.1% toluene, 0.2% non-aromatic hydrocarbons, and an olefin content of 1600 mgBr / 100g, is heat-exchanged at 200℃, 1.0 MPa, and 20.0 h⁻¹. 1 The material 3, after undergoing the deolefination reaction, enters a deolefination reactor C1 containing molecular sieve catalyst C. The resulting material 3 then enters a xylene column (top temperature 220℃, bottom temperature 282℃, pressure 1.0MPa) for separation. After 8 days of operation, a mixed xylene material 6, with an olefin content (based on the bromine index) of 10 mgBr / 100g, is separated from the top of the column. Material 2 is then transferred to a deolefination reactor C2 containing molecular sieve catalyst C (reactor C2 and reactor C1 use the same reactor and are loaded with the same amount of catalyst C) for further reaction, while simultaneously controlling the temperature at 220℃, the pressure at 1.0MPa, and the space velocity at 12.0 h⁻¹. 1 Mixed xylene material 8 is fed into reactor C1. After running for 3 days, material 8 is cut off, and then material 2 is switched to reactor C1 for reaction. Material 3, which has undergone deolefin reaction, is fed into the xylene tower for separation. Material 7 is the mixed xylene product, and the bottom material 4 is fed downstream. After the catalyst has been running for another 7.5 days, the olefin content of the mixed xylene material 6 separated from the top of the tower reaches 10 mgBr / 100g based on the bromine index.

[0072] [Example 10l]

[0073] The operation process of this embodiment is as follows: Figure 1 As shown in the figure. In order to speed up the experimental process, a catalyst deactivation test was conducted using increased space velocity.

[0074] Reformed oil, with a mass content of 50.5% mixed xylene fraction, 38.3% C9 aromatic fraction, 10.9% C10 aromatic fraction and above, 0.1% toluene, 0.2% non-aromatics, and an olefin content of 1600 mgBr / 100g (based on bromine index), was heated to a temperature of 210℃, a pressure of 1.0 MPa, and a space velocity of 18.8 h⁻¹. 1 The material 3, after undergoing the deolefination reaction, enters a deolefination reactor C1 containing catalyst C. This material then enters a xylene column (top temperature 200℃, bottom temperature 262℃, pressure 0.8MPa) for separation. After 8 days of operation, a mixed xylene material with an olefin content (bromine index) of 17 mgBr / 100g is separated at the top of the column. This mixed xylene material 8, with a bromine index of 17 mgBr / 100g, is then used as another feed to reactor C1. The reaction continues in C1, with the feed ratio of material 8 to material 1 being 0.4. The reaction product enters the xylene column for separation. After another 6 days of operation, a mixed xylene material with an olefin content of 17 mgBr / 100g, with a bromine index, is separated at the top of the column. Material 2 is then switched to a deolefination reactor C2 containing catalyst C (reactor C2 uses the same reactor as reactor C1 and is loaded with the same amount of catalyst C) for further reaction, while maintaining a temperature of 220℃ and a space velocity of 2.0 h⁻¹. 1 Mixed xylene material 8, with a pressure of 1.0 MPa, enters reactor C1. The mixture 3 from the outlets of reactors C1 and C2 enters the xylene tower for separation. After 3 days of operation, material 8 is stopped, and material 2 is switched back to reactor C1 for deolefin reaction. After the product is processed by the xylene tower, mixed xylene material 6 with an olefin content of 11 mgBr / 100g based on the bromine index is separated from the top of the tower after another 7 days of catalyst operation life.

[0075] [Example 11l]

[0076] The operation process of this embodiment is as follows: Figure 1 As shown in the figure. In order to speed up the experimental process, a catalyst deactivation test was conducted using increased space velocity.

[0077] Reformed oil, with a mass content of 50.5% mixed xylene fraction, 38.3% C9 aromatic fraction, 10.9% C10 aromatic fraction and above, 0.1% toluene, 0.2% non-aromatic hydrocarbons, and an olefin content of 1600 mgBr / 100g (based on bromine index), is heated in a heat exchanger and its temperature is controlled at 210℃, pressure at 1.0 MPa, and space velocity at 18.8 h⁻¹. 1The material 3, after undergoing the deolefin reaction, enters a deolefination reactor C1 containing catalyst D. The material 3 then enters a xylene column (top temperature 220℃, bottom temperature 282℃, pressure 1.0MPa) for separation. After 9 days of operation, a mixed xylene material with an olefin content (based on the bromine index) of 12 mgBr / 100g is separated at the top of the column. At this point, material 2 is switched to reactor C2 (reactor C2 uses the same reactor as reactor C1 and is loaded with the same amount of catalyst D), while simultaneously controlling the temperature at 220℃ and the space velocity at 3h⁻¹. 1 Mixed xylene 8, with a pressure of 1.0 MPa, is introduced into reactor C1. After running for 2 days, material 8 is cut off, and material 2 is switched back to reactor C1 for deolefin reaction. After separation by the xylene tower, the mixed xylene material 6, with an olefin content reduced to 6 mgBr / 100g based on the bromine index, is separated at the top of the tower. After the catalyst runs for another 8.7 days, the olefin content of the mixed xylene material separated at the top of the tower reaches 12 mgBr / 100g based on the bromine index.

[0078] [Example 12]

[0079] The operation process of this embodiment is as follows: Figure 1 As shown in the figure. In order to speed up the experimental process, a catalyst deactivation test was conducted using increased space velocity.

[0080] Reformed oil, with a mass content of 50.5% mixed xylene fraction, 38.3% C9 aromatic fraction, 10.9% C10 aromatic fraction and above, 0.1% toluene, 0.2% non-aromatic hydrocarbons, and an olefin content of 1600 mgBr / 100g (based on bromine index), is heated in a heat exchanger and maintained at a temperature of 210℃, a pressure of 1.0 MPa, and a space velocity of 20.0 h⁻¹. 1 The material 3, after undergoing the deolefination reaction, enters a deolefination reactor C1 containing catalyst E. This material then enters a xylene column (top temperature 220℃, bottom temperature 275℃, pressure 1.0MPa) for separation. After 5 days of operation, a mixed xylene material 6 with an olefin content (bromine index below 15mgBr / 100g) is separated at the top of the column. This mixed xylene material 8, with a bromine index of 15mgBr / 100g, is then used as another feed to reactor C1. The reaction continues in C1, with the feed ratio of material 8 to material 1 being 0.6. The reaction product enters a xylene column for further separation. After another 3 days of operation, a mixed xylene material with an olefin content (bromine index below 13mgBr / 100g) is separated at the top of the column. Then, material 2 is switched to a deolefination reactor C2 containing catalyst E (reactor C2 uses the same reactor as reactor C1 and is loaded with the same amount of catalyst E) for further reaction, while maintaining a temperature of 220℃ and a space velocity of 7.0 h⁻¹. 1Mixed xylene material 8, with a pressure of 1.0 MPa, enters reactor C1. The mixture 3 from the outlets of reactor C1 and reactor C2 enters the xylene tower for separation. After running for 2 days, material 8 is stopped, and material 2 is switched back to reactor C1 for deolefin reaction. After the product is processed by the xylene tower, the catalyst runs for another 3 days, and then mixed xylene material 6 with an olefin content of 17 mgBr / 100g based on the bromine index is separated from the top of the tower.

[0081] [Example 131]

[0082] The operation process of this embodiment is as follows: Figure 1 As shown in the figure. In order to speed up the experimental process, a catalyst deactivation test was conducted using increased space velocity.

[0083] Reformed oil, containing 50.5% mixed xylene fraction, 38.3% C9 aromatic fraction, 10.9% C10 aromatic fraction and above, 0.1 wt% toluene, 0.2% non-aromatic hydrocarbons, and an olefin content of 1600 mgBr / 100g (based on bromine index), is heated in a heat exchanger and maintained at a temperature of 210℃, a pressure of 1.0 MPa, and a space velocity of 20.0 h⁻¹. 1 The material 3, after undergoing the deolefination reaction, enters a deolefination reactor containing catalyst F. This material then enters a xylene column (top temperature 210℃, bottom temperature 262℃, pressure 0.4MPa) for separation. After 7.5 days of operation, a mixed xylene material 6 with an olefin content (bromine index below 15mgBr / 100g) is separated at the top of the column. This mixed xylene material 8, with a bromine index of 15mgBr / 100g, is then used as another feed to reactor C1. The reaction continues in reactor C1, with the feed ratio of material 8 to material 1 being 0.6. The reaction products enter a xylene column for separation. After another 4.5 days of operation, a mixed xylene material with an olefin content (bromine index below 15mgBr / 100g) is separated at the top of the column. Then, material 2 is switched to a deolefination reactor C2 containing catalyst F (reactor C2 and reactor C1 use the same reactor and are loaded with the same amount of catalyst F) for further reaction, while maintaining a temperature of 220℃ and a space velocity of 10.0 h⁻¹. 1 Mixed xylene material 8, with a pressure of 1.0 MPa, enters reactor C1. The mixture 3 from the outlets of reactor C1 and reactor C2 enters the xylene tower for separation. After running for 1 day, material 8 is stopped, and material 2 is switched back to reactor C1 for deolefin reaction. After the product is processed by the xylene tower, the catalyst is allowed to run for another 6.0 days before the mixed xylene material 6 is separated from the top of the tower. The olefin content, calculated by the bromine index, reaches 17 mgBr / 100g.

[0084] [Example 141]

[0085] Take 100g of USY molecular sieve (SiO2 / Al2O3 molar ratio of 12, pore distribution as follows: pore volume of 0.5-2.0nm accounts for 20% of the total pore volume, and pore volume of 2-50nm accounts for 15% of the total pore volume), 65g of pseudoboehmite (containing 67wt% alumina), 12g of guar gum powder, 6g of 65wt% nitric acid, and magnesium nitrate aqueous solution, knead into a mold, dry at 120℃ for 12 hours in air atmosphere, and calcine at 580℃ for 2 hours to obtain the molded body. Then, 100g of the molded body was impregnated in 50g of an impregnation solution containing tetraethyl orthosilicate (toluene as solvent). After treatment under nitrogen at 70℃ for 3 hours, the solvent was removed, and the sample was dried at 120℃ for 10 hours. Next, 100g of the sample was impregnated with an equal volume of germanium chloride in an ethanol solution, with a silica to germanium oxide mass ratio of 5.0. The sample was dried at 120℃ for 5 hours under a nitrogen atmosphere and then calcined at 550℃ for 3 hours under a nitrogen atmosphere to obtain catalyst G. The catalyst G contained 4.0% silica, 0.8% germanium oxide, and 3.0% magnesium oxide by mass.

[0086] The operation process of this embodiment is as follows: Figure 1 As shown.

[0087] Reformed oil, with a mass content of 58.5% mixed xylene fraction, 36.8% C9 aromatic fraction, 4.4% C10 aromatic fraction and above, 0.1% toluene, 0.2% non-aromatics, and an olefin content of 1200 mgBr / 100g (based on bromine index), is heated in a heat exchanger and maintained at a temperature of 205℃, a pressure of 1.0 MPa, and a space velocity of 2.1 h⁻¹. 1 The product is fed into a deolefination reactor C1 containing catalyst G for reaction. The resulting product is then fed into a xylene fractionation column (top temperature 220℃, bottom temperature 282℃, pressure 1.0 MPa) for separation. After 78 days of operation, a mixed xylene feedstock 6, with an olefin content (based on the bromine index) of 15 mgBr / 100 g, is separated at the top of the column. Feedstock 2 is then transferred to a deolefination reactor C2 containing catalyst G (reactor C2 uses the same reactor as reactor C1 and is loaded with the same amount of catalyst G) for further reaction, while maintaining a temperature of 220℃, a pressure of 1.0 MPa, and a space velocity of 1.0 h⁻¹. 1 Mixed xylene feed 8 enters the de-olefin reactor C1 containing catalyst B. The mixture 3 from the outlets of reactors C1 and C2 enters the xylene tower for separation. After 6 days of operation, feed 8 is stopped, and feed 2 is switched back to reactor C1 for de-olefin reaction. The catalyst runs for another 63 days. After the product is processed by the xylene tower, mixed xylene feed 6 is separated at the top of the tower, with an olefin content of 15 mgBr / 100g based on the bromine index.

[0088] [Example 151]

[0089] Take 100g of USY molecular sieve (SiO2 / Al2O3 molar ratio of 12, pore distribution as follows: pore volume of 0.5-2.0nm accounts for 20% of the total pore volume, pore volume of 2-50nm diameter accounts for 20% of the total pore volume), 65g of pseudoboehmite (containing 67wt% alumina), 12g of guar gum powder, and 6g of 65wt% nitric acid. Knead the mixture into a mold, dry it at 120℃ for 12 hours in air atmosphere, and calcine it at 580℃ for 2 hours to obtain the molded body. Then, 100g of the molded body was impregnated in 50g of an impregnation solution containing tetraethyl orthosilicate (toluene as solvent). After treatment under nitrogen at 70℃ for 3 hours, the solvent was removed, and the sample was dried at 120℃ for 10 hours. Next, 100g of the sample was impregnated with an equal volume of germanium chloride in an ethanol solution, with a silica to germanium oxide mass ratio of 5.0. The sample was dried at 120℃ for 5 hours under nitrogen atmosphere and then calcined at 550℃ for 3 hours under nitrogen atmosphere to obtain catalyst H. The catalyst H contained 4.0% silica and 0.8% germanium oxide by mass.

[0090] The operation process of this embodiment is as follows: Figure 1 As shown.

[0091] Reformed oil, with a mass content of 58.5% mixed xylene fraction, 36.8% C9 aromatic fraction, 4.4% C10 aromatic fraction and above, 0.1% toluene, 0.2% non-aromatics, and an olefin content of 1200 mgBr / 100g (based on bromine index), is heated in a heat exchanger and its temperature is controlled at 205℃, pressure at 1.0 MPa, and space velocity at 2.1 h⁻¹. 1 The product is fed into a deolefination reactor C1 containing catalyst H for reaction. The resulting product is then fed into a xylene fractionation column (top temperature 220℃, bottom temperature 282℃, pressure 1.0MPa) for separation. After 65 days of operation, a mixed xylene feedstock 6 with an olefin content of 15 mgBr / 100g (based on the bromine index) is separated at the top of the column. At this point, feedstock 2 is switched to a deolefination reactor C2 containing catalyst H (reactor C2 and reactor C1 use the same reactor and are loaded with the same amount of catalyst H) for reaction, while the temperature is controlled at 220℃ and the space velocity at 1.0 h⁻¹. 1 Mixed xylene feed 8, at a pressure of 1.0 MPa, enters reactor C1. The mixture 3 from the outlets of reactors C1 and C2 enters the xylene tower for separation. After 6 days of operation, feed 8 is stopped, and feed 2 is switched back to reactor C1 for deolefination. After processing in the xylene tower, the product, after a catalyst recycle of 53 days, yields mixed xylene feed 6 at the top of the tower with an olefin content (bromine index) of 15 mgBr / 100g. This process is repeated once more, resulting in a catalyst recycle of 47 days.

[0092] The embodiments described above are merely illustrative of the detailed process equipment and flow of the present invention. However, the present invention is not limited to the detailed process equipment and flow described above, meaning that the present invention does not depend on the steps described in the above embodiments for implementation. In summary, any improvements made to the present invention by those skilled in the art, including the substitution of raw materials and additives described in the present invention, and the selection of specific implementation methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for selectively removing olefin impurities from aromatic hydrocarbons, wherein at least two de-olefin reactors, namely de-olefin reactor I and de-olefin reactor II, are provided, the method comprising: (1) reforming generated oil is fed into the de-olefin reactor I and contacted with a de-olefin catalyst to perform a reaction; (2) the reaction product obtained in step (1) is fed into a xylene fractionation column to perform fractionation, and mixed xylene is obtained at the top of the column; wherein, when the content of olefins in the mixed xylene obtained in step (2) reaches 10-50 ppm, the mixed xylene obtained in step (2) is added as another feed for the de-olefin reactor I, and then, when the content of olefins in the mixed xylene obtained in step (2) reaches 10-20 ppm, the feed of reforming generated oil is switched to the de-olefin reactor II to perform a de-olefin reaction, and the mixed xylene obtained in step (2) is used as a feed for the de-olefin reactor I to regenerate the de-olefin catalyst therein; the feed temperature of the mixed xylene obtained in step (2) is 180-240℃, and the feed temperature of the mixed xylene is at least 10℃ higher than the feed temperature of the reforming generated oil; the de-olefin catalyst is a twelve-membered ring molecular sieve catalyst, and the molecular sieve catalyst comprises the following components in parts by weight: a) 50-90 parts of a molecular sieve containing a twelve-membered ring and above; b) 0.1-10 parts of an additive component, calculated as an oxide; the additive component is selected from at least one of Group IA and Group IIA; c) 0.1-10 parts of a modifying component, calculated as an oxide; the modifying component is silicon and at least one selected from germanium, bismuth, tin and boron; d) 10-49 parts of a binder component; the pore distribution of the molecular sieve is as follows: the pore volume with a pore diameter of 0.5-2.0 nm accounts for 5%-40% of the total pore volume, and the pore volume with a pore diameter of 2-50 nm accounts for 20%-50% of the total pore volume; the molecular sieve is selected from at least one of Y, β, MCM-56 and MCM-22; in the modifying component, the mass ratio of silicon, calculated as silicon oxide, to at least one selected from tin, bismuth, germanium and boron, calculated as an oxide, is 0.1-10.0; the content of olefins in the reforming generated oil, calculated as a bromine index, is 200-2800 mgBr / 100g; the de-olefin reactor I or the de-olefin reactor II is a fixed bed reactor, wherein the de-olefin catalyst is loaded; the operating conditions of the xylene fractionation column in step (2) are as follows: the temperature at the top of the column is 200-250℃, the temperature at the bottom of the column is 230-295℃, and the pressure is 0.4-1.2 MPa; when the content of olefins in the mixed xylene obtained in step (2) reaches 10-50 ppm, the amount of the mixed xylene obtained in step (2) as another feed for the de-olefin reactor I is 0.01-1.0 times the mass of the feed of the reforming generated oil; the amount of the mixed xylene obtained in step (2) as another feed for the de-olefin reactor I is 0.1-0.5 times the mass of the feed of the reforming generated oil; after the de-olefin catalyst in the de-olefin reactor I is regenerated, the feed is switched to the reforming generated oil to perform the de-olefin reaction in step (1). ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2. The method of claim 1, wherein, ​ 3. The method of claim 1, wherein, ​ 4. The method of claim 1, wherein, The reaction conditions of the reaction in step (1) are as follows: temperature is 140-230°C, pressure is 0.3-5.0 MPa, liquid hourly space velocity is 0.2-20 h -1 .

5. The method of claim 1, wherein, ​ 6. The method of claim 1, wherein, ​ 7. The method of claim 1, wherein, ​ 8. The method of claim 1, wherein, When the olefin content in the mixed xylene obtained in step (2) reaches 10-20 ppm, the reformate feed is switched to the deolefinization reactor II for deolefinization reaction, and the mixed xylene obtained in step (2) is used as the feed of the deolefinization reactor I for regeneration of the deolefinization catalyst therein, and the operating conditions of the deolefinization reactor I are as follows: temperature 200-230°C, pressure 0.5-5.0 MPa, liquid hourly space velocity 0.2-5.0 h -1 , and regeneration time 1-300 hours.

9. The method of claim 1, wherein, ​

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