Mixed xylene olefin removal catalyst as well as preparation method and application thereof

Abstract

The preparation method comprises the following steps: firstly, impregnating organic amine or organic amine salt on a molecular sieve matrix by adopting an equivalent-volume impregnation method to prepare a modified molecular sieve, and then carrying out hydrothermal treatment on the modified molecular sieve by adopting an alkaline solution to prepare an active component, and finally, uniformly mixing the active component and the binder, acidifying and peptizing, kneading, extruding and molding, drying and roasting to obtain the mixed xylene olefin removal catalyst. The catalyst prepared by the invention can effectively remove trace olefin in mixed xylene under a non-hydrogen condition; the catalyst can reduce the bromine index of the raw material by at least 70%, has the advantages of high activity, long service life, high hydrothermal stability and less aromatic loss, and prolongs the service life of the olefin removal catalyst to the greatest extent.

Description

Technical Field

[0001] The invention belongs to the field of deolefination catalysts, and in particular relates to a mixed xylene deolefination catalyst and a preparation method and application thereof. Background Art

[0002] There are often trace amounts of olefins in mixed xylene oil products. It is very necessary to remove these olefins. First, the product requires a certain degree of purity of olefin impurities. If these olefins are not removed, they will most likely react with aromatics to generate non-ideal components, thus having a significant impact on the quality of the aromatic products. Second, removing trace olefin impurities will also protect subsequent processes that are sensitive to the presence of olefins, such as the molecular sieve adsorption separation process. Trace olefin impurities will occupy the gaps in the molecular sieve, thus affecting its separation performance.

[0003] At present, the main methods for removing olefin impurities in mixed xylene are hydrofining and clay refining. Hydrofining is to use precious metal platinum or palladium catalysts to perform a "post-hydrogenation process" on the reformed oil after the petroleum reforming process to saturate the olefins and remove olefin impurities. However, hydrofining technology has the disadvantages of large construction investment, high operating costs, and high aromatic losses. Clay refining is to use activated clay to remove trace olefins in reformed aromatics. This is because clay has active acid centers. Under high-pressure liquid phase and 150-200°C conditions, it has certain catalytic superposition ability and pore adsorption ability, which can make the trace olefins contained in the reformed oil undergo hydrocarbonization, polymerization and other reactions to generate high-boiling point compounds, which are then adsorbed by clay or removed in subsequent separation processes. However, clay has low activity and short life, and needs to be replaced frequently, resulting in a very large amount of clay used and high labor intensity, which seriously restricts the "long-term, stable and excellent" operation of the device. In recent years, with the promotion of low-pressure reforming technology, the olefin content in reformed oil has further increased, and the above problems will be further aggravated.

[0004] Since molecular sieves have regular pore structures and suitable acid properties, they are widely used in acid-catalyzed reactions. The process of removing reforming oil olefins using molecular sieve catalysts is the same as the clay refining process and process conditions, so molecular sieve catalysts can well make up for the shortcomings of the above two traditional processes.

[0005] CN200410046820.0 proposes a catalyst for removing olefins from reformed aromatic oil using molecular sieve as an active component and alumina as a binder. The catalyst can effectively remove trace olefins from aromatics when used to treat reformed aromatic oil. Aromatics are not lost but increased, especially C8 aromatics. However, the catalyst still has the disadvantages of low activity and short life.

[0006] CN101433856A proposes using Y-type and β-type molecular sieves loaded with rare earth, P, Mo, etc. as catalysts for removing trace olefins from aromatic hydrocarbons. Compared with industrial clay, the olefin removal capacity is improved. Under the same comparative conditions, the olefin removal time is extended by nearly 3 times.

[0007] Wang Yinan et al. conducted a study on the removal of trace olefins from aromatic hydrocarbons by zeolite molecular sieves in the study of "Research on the removal of trace olefins from aromatic hydrocarbons by zeolite molecular sieves". The olefin impurities in aromatic hydrocarbons were deeply removed by using zeolite molecular sieve catalysts modified by the rare earth element La. The experimental results show that the mechanical mixing method is the best catalyst; for Z-type molecular sieves, the optimal addition mass fraction of the rare earth element La is 10%, and the initial activity and life are greatly improved.

[0008] The above catalysts use molecular sieve as the main active component, but when the content of colloid and olefin in mixed xylene is high, the life of molecular sieve catalyst is rapidly shortened, and the accuracy of catalyst in removing olefin is reduced, and the best effect of use cannot be achieved, resulting in waste of catalyst and increased regeneration frequency, which not only greatly increases the cost, but also causes environmental pollution due to the treatment and disposal of a large number of catalysts. This is because the micropores of molecular sieve reduce the diffusion of reactants and products, thereby reducing the service life of the catalyst. At the same time, the hydrothermal stability of molecular sieve catalyst is poor. After multiple regenerations, the overall performance of the catalyst is greatly reduced, and it cannot continue to be used in industrial production and can only be treated as hazardous waste.

[0009] Therefore, based on these problems, it is of great practical significance to provide a method and a catalyst that can not only increase the mesopore ratio of the mixed xylene deolefination catalyst, but also increase the hydrothermal stability of the catalyst, thereby extending the service life of the catalyst and increasing the number of catalyst regeneration times. Summary of the invention

[0010] The present invention is proposed to solve the problems existing in the prior art, and its purpose is to provide a mixed xylene deolefination catalyst and a preparation method and application thereof.

[0011] The present invention is achieved through the following technical solutions: A method for preparing a mixed xylene deolefination catalyst comprises the following steps: (i) preparing an organic amine or organic amine salt aqueous solution, then slowly adding a molecular sieve precursor to the organic amine or organic amine salt aqueous solution, mixing evenly, stirring at 30° C. to 100° C. for 2 h to 8 h, and then drying at 60° C. to 150° C. for 10 h to prepare a modified molecular sieve; (ii) preparing an alkaline solution, adding the modified molecular sieve to the alkaline solution, stirring and mixing the solution, performing a hydrothermal treatment, filtering, washing, ammonium exchange and drying to obtain an active component; The ammonium exchange method is specifically as follows: using 0.2 mol / L to 0.35 mol / L ammonium sulfate solution at a solid-liquid ratio (mass ratio) of 1:10, performing ammonium exchange three times at 80° C., each time for 2 hours; The drying conditions are: drying at 100°C to 180°C for 6h to 15h; (iii) The active component and the binder are mixed uniformly, diluted nitric acid is added for kneading, acidification and peptization and extrusion molding, and the mixture is dried at 100°C to 150°C for 6h to 12h and calcined at 550°C for 4h to 10h to obtain a mixed xylene deolefination catalyst.

[0012] In the above technical solution, the molecular sieve matrix is ​​any one of MCM-22 molecular sieve, MCM-56 molecular sieve, MCM-49 molecular sieve, ultra-stable Y-type molecular sieve or Beta molecular sieve, or a mixture of several of them.

[0013] In the above technical solution, the organic amine or organic amine salt is any one of cyclohexylamine, aniline, piperidine, hexamethyleneimine, tetrapropylammonium bromide, tetraethylammonium bromide or tetramethylammonium bromide, or a mixture of several of them.

[0014] In the above technical solution, the molar ratio of the organic amine or organic ammonium salt to the molecular sieve matrix is ​​(0.02-0.3):1, and the water used to dissolve the organic amine or organic ammonium salt is the saturated adsorption water amount of the molecular sieve matrix.

[0015] In the above technical solution, the alkaline source of the alkaline solution is any one of ethylamine, ammonia water, ethylenediamine, NaOH, TMAOH (tetramethylammonium hydroxide), TEAOH (tetraethylammonium hydroxide) or TPAOH (tetrapropylammonium hydroxide) or a mixture of several thereof.

[0016] In the above technical solution, the concentration of the alkaline solution is 0.01 mol / L~0.3 mol / L.

[0017] In the above technical solution, the mass ratio of the modified molecular sieve to the alkaline solution is 1:10.

[0018] In the above technical solution, the hydrothermal treatment conditions in step (ii) are: hydrothermal treatment at 60°C~180°C for 20h~72h; the preferred hydrothermal treatment conditions are: hydrothermal treatment at 70°C~170°C for 6h~60h.

[0019] In the above technical solution, the mass ratio of the active component to the binder is (10-80): (20-90).

[0020] In the above technical solution, the binder is any one of macroporous silica, mesoporous silica, macroporous alumina, mesoporous alumina or amorphous silica-alumina or a mixture of several of them.

[0021] In the above technical solution, the ratio of the pore volume of the larger pores to that of the smaller pores in the pore volume of the active component is (0.2 to 10):1; the pore diameter of the larger pores is 10 nm to 30 nm, and the pore diameter of the smaller pores is 2 nm to 10 nm.

[0022] In the above technical solution, the mass concentration of the dilute nitric acid is 2% to 5%, and the mass ratio of the addition amount of the dilute nitric acid to the active component is (1.2 to 1.6):1.

[0023] A catalyst for removing olefins from mixed xylene prepared by the aforementioned method, using the NH 3 -TPD characterization result, the amount of strong acid sites of the catalyst for removing olefins from mixed xylene accounts for 23% to 39% of the total acid amount, preferably 29% to 35%.

[0024] An application of a catalyst for removing olefins from mixed xylene prepared by the aforementioned method in removing trace olefins from reformed product oil, and the olefin removal reaction conditions are: the temperature is 130°C to 240°C, the pressure is 1 MPa to 5 MPa in gauge pressure, and the volume space velocity is 1 h -1 ~50 h -1 .

[0025] The beneficial effects of the present invention are: The present invention provides a catalyst for removing olefins from mixed xylene and its preparation method and application. The catalyst prepared by the present invention can effectively remove trace olefins in mixed xylene under non-hydrogenation conditions; the catalyst can reduce the bromine index of the raw material by at least 70%, and the catalyst has high activity, long service life, high hydrothermal stability and less aromatic loss, and maximally extends the service life of the olefin removal catalyst.

[0026] By loading template agent molecules, the present invention improves the protection of the framework structure during the treatment of molecular sieves with an alkaline solution, and maximally obtains a through-hole size distribution beneficial to the diffusion of macromolecules; at the same time, during the alkaline treatment process, by directionally adjusting the number and distribution of Al atoms, the number and strength of B acid sites of the molecular sieve are controllably adjusted, and more L acid sites are generated. While providing more active sites for the catalyst, side reactions such as coking and carbon deposition of strong B acid sites are avoided, so that the activity and stability of the catalyst are significantly improved; through the protection of the template agent, the yield of molecular sieves during the alkaline treatment process is improved, and the production cost is maximally reduced; during the catalyst forming process, the binder is a mesoporous or macroporous material, which is coupled with the active component, maximally improves the diffusion performance of reactants and products, and improves the service life of the catalyst. Specific Embodiments

[0027] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be further described below through specific embodiments.

[0028] Example 1 A method for preparing a mixed xylene deolefination catalyst comprises the following steps: (i) Dissolve 10 g of tetramethylammonium bromide in 900 g of water and stir to dissolve it completely. Then weigh 100 g of MCM-22 molecular sieve and dissolve it in the tetramethylammonium bromide solution. After stirring in a 70°C water bath for 2 h, place it in a 60°C oven and dry it for 10 h to obtain a modified MCM-22 molecular sieve with a tetramethylammonium bromide content of 10%.

[0029] (ii) Weigh 72g of tetramethylammonium hydroxide (25wt%) and dissolve it in 1000g of deionized water. After stirring and dissolving, add 100g of modified MCM-22 molecular sieve according to a solid-liquid ratio of 1:10, stir for 5min to make it completely uniform, transfer the modified solution to a water bath, heat it to 70°C, and carry out modification treatment under dynamic stirring conditions. After reacting for 2h, the modified solution is filtered, washed, dried, and calcined to obtain a mesoporous MCM-22 molecular sieve, and then the MCM-22 molecular sieve is exchanged for 2h with a 0.2mol / L ammonium sulfate solution according to a solid-liquid ratio of 1:10. After 3 exchanges, the product is filtered, washed, dried, and calcined to obtain a hydrogen-type MCM-22 molecular sieve; (iii) 115 g of hydrogen-type MCM-22 molecular sieve, 62 g of mesoporous alumina and 1 g of sesbania powder were mixed uniformly, and then 150 g of a 2% by mass dilute nitric acid solution was added and kneaded thoroughly to make a paste-like plastic material. The cylindrical strips with a diameter of 2 mm were extruded on an extruder. The cylindrical strips were dried at 120°C for 16 h and then calcined at 550°C in an air atmosphere for 4 h to obtain catalyst T-1. 3 -TPD characterization shows that the strong acid content of T-1 catalyst accounts for 25% of the total acid content.

[0030] A method for removing olefins from reforming oil, specifically: contacting catalyst T-1 with reforming oil containing olefins to carry out a deolefination reaction, the raw material bromine index is 1000mgBr / 100g oil, and the reaction conditions include: temperature 180°C, pressure gauge pressure 2.0MPa, mass space velocity 15h -1 The catalyst was deactivated after 320 hours of reaction, with the export bromine index of 300 mg Br / 100 g oil as the standard. After the reaction, the catalyst was regenerated by charring, that is, calcined at 550°C in air atmosphere for 4 hours, and then the regenerated catalyst was evaluated under the same reaction conditions and requirements as above, with a life of 230 hours.

[0031] Example 2 A method for preparing a mixed xylene deolefination catalyst comprises the following steps: (i) Dissolve 13 g of piperidine in 900 g of water and stir to completely dissolve it. Then weigh 100 g of MCM-56 molecular sieve and dissolve it in the piperidine solution. After stirring in a 40°C water bath for 8 h, place it in a 60°C oven and dry it for 10 h to obtain a modified MCM-56 molecular sieve with a tetramethylammonium bromide content of 13%.

[0032] (ii) Weigh 4.87 g of sodium hydroxide (98.5 wt%) and dissolve it in 1000 g of deionized water. After stirring and dissolving, add 100 g of modified MCM-56 molecular sieve at a solid-liquid ratio of 1:10, stir for 5 min to make it completely uniform, transfer the modified solution to a water bath, heat it to 150 ° C, and carry out modification treatment under dynamic stirring conditions. After reacting for 36 hours, the modified solution is filtered, washed, dried, and calcined to obtain mesoporous MCM-56 molecular sieve, and then the MCM-56 molecular sieve is exchanged with 0.2 mol / L ammonium sulfate solution for 2 hours at a solid-liquid ratio of 1:10. After 3 exchanges, the product is filtered, washed, dried, and calcined to obtain hydrogen-type MCM-56 molecular sieve.

[0033] (iii) 100 g of hydrogen-type MCM-56 molecular sieve, 90 g of alumina and 0.87 g of sesbania powder were mixed evenly, and then 150 g of a 2% by mass dilute nitric acid solution was added and kneaded thoroughly to make a paste-like plastic material, and cylindrical strips with a diameter of 2 mm were extruded on an extruder. The cylindrical strips were dried at 120°C for 16 h, and then calcined at 550°C in an air atmosphere for 4 h to obtain catalyst T-2. 3 -TPD characterization shows that the strong acid content of T-2 catalyst accounts for 36% of the total acid content.

[0034] A method for removing olefins from reforming oil, specifically: contacting the catalyst T-2 with the reforming oil containing olefins to carry out a deolefination reaction, the raw material bromine index is 1000mgBr / 100g oil, and the reaction conditions include: temperature 180°C, pressure gauge pressure 2.0MPa, mass space velocity 15h -1 The catalyst was deactivated after 380 hours of reaction, with the export bromine index of 300 mg Br / 100 g oil as the standard. After the reaction, the catalyst was regenerated by charring, that is, calcined at 550°C in air atmosphere for 4 hours, and then the regenerated catalyst was evaluated under the same reaction conditions and requirements as above, with a life of 247 hours.

[0035] Example 3 A method for preparing a mixed xylene deolefination catalyst comprises the following steps: (i) Dissolve 20 g of cyclohexylamine in 900 g of water and stir to completely dissolve it. Then weigh 100 g of MCM-22 molecular sieve and dissolve it in tetramethylammonium bromide solution. After stirring in a 30°C water bath for 6 h, place it in a 70°C oven and dry it for 10 h to obtain a modified MCM-56 molecular sieve with a cyclohexylamine content of 20%.

[0036] (ii) Weigh 27.2 g of ammonia water (25 wt%) and dissolve it in 1000 g of deionized water. After stirring and dissolving, add 10 g of modified MCM-56 molecular sieve at a solid-liquid ratio of 1:10, stir for 5 min to make it completely uniform, transfer the modified solution to a water bath, heat it to 180 ° C, and carry out modification treatment under dynamic stirring conditions. After reacting for 72 hours, the modified solution is filtered, washed, dried, and calcined to obtain mesoporous MCM-56 molecular sieve, and then the MCM-56 molecular sieve is exchanged with 0.2 mol / L ammonium sulfate solution for 2 hours at a solid-liquid ratio of 1:10. After 3 exchanges, the product is filtered, washed, dried, and calcined to obtain hydrogen-type MCM-56 molecular sieve.

[0037] (iii) 100 g of hydrogen-type MCM-56 molecular sieve, 504 g of amorphous silicon-alumina and 0.87 g of sesbania powder were mixed evenly, and then 480 g of a 2% by mass dilute nitric acid solution was added and kneaded thoroughly to make a paste-like plastic material, which was extruded into cylindrical strips with a diameter of 2 mm on an extruder. The cylindrical strips were dried at 120°C for 16 h, and then calcined at 550°C in an air atmosphere for 4 h to obtain catalyst T-3. NH 3 -TPD characterization shows that the strong acid content of T-3 catalyst accounts for 28% of the total acid content.

[0038] A method for removing olefins from reforming oil, specifically: contacting the catalyst T-3 with the reforming oil containing olefins to carry out a deolefination reaction, the raw material bromine index is 1000mgBr / 100g oil, and the reaction conditions include: temperature 180°C, pressure gauge pressure 2.0MPa, mass space velocity 15h -1 The catalyst was deactivated after 150 hours of reaction, with the export bromine index of 300 mg Br / 100 g oil as the standard. After the reaction, the catalyst was regenerated by charring, that is, calcined at 550°C in air atmosphere for 4 hours, and then the regenerated catalyst was evaluated under the same reaction conditions and requirements as above, with a life of 120 hours.

[0039] Example 4 A method for preparing a mixed xylene deolefination catalyst comprises the following steps: (i) Dissolve 10 g of aniline in 900 g of water and stir to completely dissolve it. Then weigh 100 g of MCM-49 molecular sieve and dissolve it in the aniline solution. After stirring in a water bath at 80°C for 6 h, place it in an oven at 60°C and dry it for 10 h to obtain a modified MCM-49 molecular sieve with a tetramethylammonium bromide content of 10%.

[0040] (ii) Weigh 30 g of ethylenediamine (99 wt%) and dissolve it in 1000 g of deionized water. After stirring and dissolving, add 100 g of modified MCM-49 molecular sieve at a solid-liquid ratio of 1:10, stir for 5 min to make it completely uniform, transfer the modified solution to a water bath, heat it to 120 ° C, and carry out modification treatment under dynamic stirring conditions. After reacting for 10 h, the modified solution is filtered, washed, dried, and calcined to obtain a mesoporous MCM-49 molecular sieve. Then, the MCM-49 molecular sieve is exchanged with 0.2 mol / L ammonium sulfate solution for 2 h at a solid-liquid ratio of 1:10. After 3 exchanges, the product is filtered, washed, dried, and calcined to obtain a hydrogen-type MCM-49 molecular sieve.

[0041] (iii) 100 g of hydrogen-type MCM-49 molecular sieve, 126 g of mesoporous silica and 0.87 g of sesbania powder were mixed evenly, and then 200 g of a 2% by mass dilute nitric acid solution was added and kneaded thoroughly to make a paste-like plastic material, and then cylindrical strips with a diameter of 2 mm were extruded on an extruder. The cylindrical strips were dried at 120°C for 16 h, and then calcined at 550°C in an air atmosphere for 4 h to obtain catalyst T-4. NH 3 -TPD characterization shows that the strong acid content of T-4 catalyst accounts for 39% of the total acid content.

[0042] A method for removing olefins from reforming oil, specifically: contacting the catalyst T-4 with the reforming oil containing olefins to carry out a deolefination reaction, the raw material bromine index is 1000 mgBr / 100g oil, and the reaction conditions include: temperature of 180°C, pressure of 2.0 MPa on a pressure gauge, and mass space velocity of 15 h -1 The catalyst was deactivated after 280 hours of reaction, with the export bromine index of 300 mg Br / 100 g oil as the standard. After the reaction, the catalyst was regenerated by charring, that is, calcined at 550°C in air atmosphere for 4 hours, and then the regenerated catalyst was evaluated under the same reaction conditions and requirements as above, with a life of 210 hours.

[0043] Example 5 A method for preparing a mixed xylene deolefination catalyst comprises the following steps: (i) Dissolve 2 g of tetrapropylammonium bromide in 230 g of water and stir to dissolve it completely. Then weigh 100 g of ultra-stable Y molecular sieve and dissolve it in tetramethylammonium bromide solution. After stirring in a 40°C water bath for 2 h, place it in an oven at 80°C and dry it for 10 h to obtain a modified ultra-stable Y molecular sieve with a tetrapropylammonium bromide content of 2%.

[0044] (ii) Weigh 9 g of ethylamine (99 wt%) and dissolve it in 1000 g of deionized water. After stirring and dissolving, add 100 g of modified ultra-stable Y molecular sieve at a solid-liquid ratio of 1:10, stir for 5 min to make it completely uniform, transfer the modified solution to a water bath, heat it to 60 ° C, and carry out modification treatment under dynamic stirring conditions. After reacting for 20 h, the modified solution is filtered, washed, dried, and calcined to obtain a mesoporous ultra-stable Y molecular sieve, and then the ultra-stable Y molecular sieve is exchanged with 0.2 mol / L ammonium sulfate solution for 2 h at a solid-liquid ratio of 1:10. After 3 exchanges, the product is filtered, washed, dried, and calcined to obtain a hydrogen-type ultra-stable Y molecular sieve.

[0045] (iii) 100 g of hydrogen-type ultrastable Y molecular sieve, 54 g of silicon oxide and 0.87 g of sesbania powder were mixed uniformly, and then 140 g of a 2% by mass dilute nitric acid solution was added and kneaded thoroughly to make a paste-like plastic material, and cylindrical strips with a diameter of 2 mm were extruded on an extruder. The cylindrical strips were dried at 120°C for 16 h, and then calcined at 550°C in an air atmosphere for 4 h to obtain catalyst T-5. NH 3 -TPD characterization shows that the strong acid content of T-1 catalyst accounts for 32% of the total acid content.

[0046] A method for removing olefins from reforming oil, specifically: contacting the catalyst T-5 with the reforming oil containing olefins to carry out a deolefination reaction, the raw material bromine index is 1000 mgBr / 100g oil, and the reaction conditions include: temperature of 180°C, pressure of 2.0 MPa on a pressure gauge, and mass space velocity of 15 h -1 The catalyst was deactivated after 140 hours of reaction, with the export bromine index of 300 mg Br / 100 g oil as the standard. After the reaction, the catalyst was regenerated by charring, that is, calcined at 550°C in air atmosphere for 4 hours, and then the regenerated catalyst was evaluated under the same reaction conditions and requirements as above, with a life of 126 hours.

[0047] Example 6 A method for preparing a mixed xylene deolefination catalyst comprises the following steps: (i) 30 g of tetraethylammonium bromide was dissolved in 230 g of water and stirred to completely dissolve. Then 100 g of Beta molecular sieve was weighed and dissolved in the tetramethylammonium bromide solution. After stirring in a 40°C water bath for 8 h, it was placed in an oven at 80°C and dried for 48 hours to obtain a modified Beta molecular sieve with a tetramethylammonium bromide content of 2%.

[0048] (ii) Weigh 11.8 g of tetraethylammonium hydroxide (25 wt%) and dissolve it in 1000 g of deionized water. After stirring and dissolving, add 100 g of modified Beta molecular sieve at a solid-liquid ratio of 1:10, stir for 5 min to make it completely uniform, transfer the modified solution to a water bath, heat it to 80 ° C, and carry out modification treatment under dynamic stirring conditions. After reacting for 4 hours, the modified solution is filtered, washed, dried, and calcined to obtain a mesoporous Beta molecular sieve. Then, the Beta molecular sieve is exchanged with 0.2 mol / L ammonium sulfate solution for 2 hours at a solid-liquid ratio of 1:10. After 3 exchanges, the product is filtered, washed, dried, and calcined to obtain a hydrogen-type Beta molecular sieve.

[0049] (iii) 100 g of hydrogen-type Beta molecular sieve, 31.52 g of mesoporous alumina and 0.87 g of sesbania powder were mixed uniformly, and then 120 g of a 2% by mass dilute nitric acid solution was added and kneaded thoroughly to make a paste-like plastic material, and cylindrical strips with a diameter of 2 mm were extruded on an extruder. The cylindrical strips were dried at 120°C for 16 h, and then calcined at 550°C in an air atmosphere for 4 h to obtain catalyst T-6. NH 3 -TPD characterization shows that the strong acid content of T-6 catalyst accounts for 29% of the total acid content.

[0050] A method for removing olefins from reforming oil, specifically: contacting the catalyst T-6 with the reforming oil containing olefins to carry out a deolefination reaction, the raw material bromine index is 1000mgBr / 100g oil, and the reaction conditions include: temperature of 180°C, pressure of 2.0MPa on a pressure gauge, mass space velocity of 15h -1 The catalyst was deactivated after 180 hours of reaction, with the export bromine index of 300 mg Br / 100 g oil as the standard. After the reaction, the catalyst was regenerated by charring, that is, calcined at 550°C in air atmosphere for 4 hours, and then the regenerated catalyst was evaluated under the same reaction conditions and requirements as above, with a life of 153 hours.

[0051] Comparative Example 1 Catalyst C-1 was prepared by enlarging the comparative example CN112337505A, i.e., CeY molecular sieve exchanged with metal cerium was uniformly mixed with MCM-41 molecular sieve, alumina, sesbania powder, citric acid and dilute nitric acid, kneaded, extruded into a strip cylinder with a diameter of 1.5 mm, and calcined at 620°C for 2 hours to obtain catalyst C-1.

[0052] The method for removing olefins from reforming oil comprises: contacting the catalyst C-1 with the reforming oil containing olefins to carry out a deolefination reaction, wherein the bromine index of the raw material is 1000 mgBr / 100 g oil, and the reaction conditions include: a temperature of 180°C, a pressure gauge pressure of 2.0 MPa, and a mass space velocity of 15 h-1 The catalyst was deactivated after 60 hours of reaction, with the export bromine index of 300 mg Br / 100 g oil as the standard. After the reaction, the catalyst was regenerated by charring, that is, calcined at 550°C in air atmosphere for 4 hours, and then the regenerated catalyst was evaluated under the same reaction conditions and requirements as above, with a life of 54 hours.

[0053] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a mixed xylene deolefination catalyst, characterized in that: The following steps are involved: (i) preparing an organic amine or an organic amine salt solution, adding a molecular sieve precursor to the organic amine or the organic amine salt solution, mixing evenly, stirring, drying and calcining to prepare a modified molecular sieve; (ii) preparing an alkaline solution, adding the modified molecular sieve to the alkaline solution, stirring and mixing the solution, performing a hydrothermal treatment, filtering, washing, ammonium exchange and drying to obtain an active component; (iii) The active component and the binder are mixed uniformly, diluted nitric acid is added for kneading, acidification and peptization, and extrusion molding, and then drying and calcining are performed to obtain a mixed xylene deolefination catalyst.

2. The method for preparing a mixed xylene deolefination catalyst according to claim 1, characterized in that: The molecular sieve matrix is ​​any one of MCM-22 molecular sieve, MCM-56 molecular sieve, MCM-49 molecular sieve, ultra-stable Y-type molecular sieve or Beta molecular sieve, or a mixture of several thereof; The organic amine or organic amine salt is any one of cyclohexylamine, aniline, piperidine, hexamethyleneimine, tetrapropylammonium bromide, tetraethylammonium bromide or tetramethylammonium bromide, or a mixture of several thereof; The molar ratio of the organic amine or organic ammonium salt to the molecular sieve matrix is ​​(0.02-0.3): 1, The solvent of the organic amine or organic amine salt solution is water, and the amount of the solvent is the saturated adsorption water amount of the molecular sieve matrix.

3. The method for preparing a mixed xylene deolefination catalyst according to claim 1, characterized in that: The alkaline source of the alkaline solution is any one or a mixture of ethylamine, ammonia water, ethylenediamine, NaOH, TMAOH, TEAOH or TPAOH; The concentration of the alkaline solution is 0.01 mol / L to 0.3 mol / L.

4. The method for preparing a mixed xylene deolefination catalyst according to claim 1, characterized in that: The mass ratio of the modified molecular sieve to the alkaline solution is 1:10; The conditions of the hydrothermal treatment in step (ii) are: hydrothermal treatment at 60°C to 180°C for 20h to 72h.

5. The method for preparing a mixed xylene deolefination catalyst according to claim 1, characterized in that: The mass ratio of the active component to the binder is (10-80):(20-90).

6. The method for preparing a mixed xylene deolefination catalyst according to claim 1, characterized in that: The binder is any one of macroporous silica, mesoporous silica, macroporous alumina, mesoporous alumina or amorphous silica-alumina or a mixture of several of them.

7. The method for preparing a mixed xylene deolefination catalyst according to claim 1, characterized in that: The ratio of the pore volume of the larger pores to the smaller pores in the pore volume of the active component is (0.2-10):1; the pore diameter of the larger pores is 10nm-30nm, and the pore diameter of the smaller pores is 2nm-10nm.

8. The method for preparing a mixed xylene deolefination catalyst according to claim 1, characterized in that: The mass concentration of the dilute nitric acid is 2% to 5%, and the mass ratio of the added amount of the dilute nitric acid to the active component is (1.2 to 1.6):

1.

9. A mixed xylene deolefination catalyst prepared by the method according to any one of claims 1 to 8, characterized in that: According to the NH3-TPD characterization results, the strong acid content of the mixed xylene deolefination catalyst accounts for 23% to 39% of the total acid content.

10. Use of a mixed xylene deolefination catalyst prepared by the method according to any one of claims 1 to 8 in removing trace olefins from reforming oil, characterized in that: The deolefination reaction conditions are: temperature of 130°C to 240°C, pressure of 1MPa to 5MPa, and volume space velocity of 1h -1 ~50h -1 .