CN103012036B - Aromatic hydrocarbon purifying method - Google Patents

Abstract

The invention discloses a method for refining aromatic hydrocarbons. The method is as follows: under the conditions of temperature 50-400°C, pressure 0.1-12MPa, and feed mass space velocity 0.1-15 hours ^-1 , aromatic hydrocarbons and solid acid catalyst Contact reaction to obtain refined aromatics; the invention has a simple process flow, does not consume hydrogen, and has low equipment investment and operating costs; the catalyst has good activity stability, long stable operation time of the equipment, less loss of aromatics, and frequent reactor reactions and regenerations can be avoided By switching operation, the catalyst can be regenerated, which can avoid landfill disposal of a large number of spent catalysts, and has little impact on the environment.

Description

A method for refining aromatics

(1) Technical field

The invention relates to a method for refining aromatic hydrocarbons, in particular to a method for removing trace olefins in aromatic hydrocarbons by using a core-shell molecular sieve catalyst for acid-catalyzed reaction.

(2) Background technology

Aromatic hydrocarbons are important chemical basic raw materials, and the petrochemical industry produces aromatic hydrocarbons through processes such as naphtha reforming and steam cracking. A certain amount of olefin impurities (less than 1%) exist in the aromatic products of these processes. This part of olefin impurities affects the quality of aromatic products and has adverse effects on some subsequent chemical processes. Therefore, in order to obtain qualified aromatic hydrocarbon raw materials and ensure the smooth progress of subsequent processes, it is necessary to deeply remove the olefin impurities in aromatic hydrocarbons. At present, the methods widely used by refineries at home and abroad to remove olefin impurities in aromatics products mainly include hydrorefining and clay refining.

Hydrofining mainly uses platinum or palladium catalyst supported by alumina carrier, and carries out a "post-hydrogenation" process behind the reforming reactor to achieve olefin saturation and achieve the purpose of removing olefins. The efficiency of hydrotreating to remove olefin impurities is high, so it is widely used by domestic and foreign refineries. For the benzene fraction, whether platinum or palladium is used as the active component, the effect is better, but for the wide fraction of aromatics such as benzene, toluene and xylene, it is difficult to fully consider the depth of hydrogenation reaction, and the aromatics are more significant. Loss. And its process is more complicated, it must be equipped with many hydrogen-facing high-pressure equipment, plus some noble metal catalysts, resulting in high investment and operating costs.

Clay refining is the use of acid-treated clay to remove olefins from aromatics mainly through adsorption or partial olefin stacking and alkylation reactions. Although the refining method of clay has been widely used in industry, the effect of removing olefins is relatively poor; in the actual treatment process, clay deactivation is fast, the use period is short, and the dosage is large, and the clay after deactivation cannot be regenerated, about 1 month Just need to replace new clay, frequent replacement increases the loss of aromatics and workload, and a large amount of waste clay needs to be dumped, causing environmental pollution.

Microporous molecular sieves can be used as catalysts for removing trace olefins in aromatics due to their strong surface acidity and hydrothermal stability. Just because the pore size is too small, the internal diffusion resistance of larger molecules generated by reactions such as olefin superposition is relatively large, resulting in a high rate of coking and deactivation of the catalyst, and poor stability of the catalyst activity. The SBA-15 type mesoporous molecular sieve has attracted widespread attention because of its highly ordered mesoporous structure, which can increase the diffusion rate of macromolecular reactants in its channels. However, due to the poor hydrothermal stability and acidity of this mesoporous molecular sieve, its application in petrochemical industry is hindered. Combining microporous molecular sieves and mesoporous molecular sieves has practical significance, and can exert the strong surface acidity and hydrothermal stability of microporous molecular sieves, and the strong diffusion performance of mesoporous molecular sieves. The microporous molecular sieve is used as the core, and the SBA-15 phase grows on the outer surface of the microporous molecular sieve core, forming a composite molecular sieve with a core-shell multi-level pore structure. Due to the symbiosis of the two phases of mesoporous pores, the wall of the mesoporous pores becomes thicker, which improves the thermal and hydrothermal stability of the mesoporous molecular sieves. The microporous-mesoporous composite molecular sieve has both the strong acidity of the microporous molecular sieve wall structure and the large mesoporous aperture, which enhances the synergy between molecular sieves and overcomes the problem of catalyst deactivation caused by the channel limitation of microporous molecular sieves. Improve the activity and stability of the catalyst.

(3) Contents of the invention

The purpose of the present invention is to provide a method for removing trace olefins in aromatic hydrocarbons which is environmentally friendly, has good catalyst activity stability and long stable operation time.

The technical scheme adopted in the present invention is:

A method for refining aromatic hydrocarbons, the method comprising: contacting and reacting aromatic hydrocarbons with a solid acid catalyst under the conditions of a temperature of 50-400°C, a pressure of 0.1-12 MPa, and a feed mass space velocity of 0.1-15 hours ^-1 , to make the aromatic hydrocarbons Trace olefins in the catalyst undergo adsorption, stacking and alkylation reactions to remove trace olefins in aromatics, thereby refining aromatics and obtaining refined aromatics; the solid acid catalyst is a core-shell type in which the shell wraps the core Composite molecular sieve catalysts or composite solid acid catalysts obtained by loading modified compounds on core-shell composite molecular sieve catalysts;

The core-shell composite molecular sieve catalyst is prepared as follows: according to the solid-to-liquid mass ratio of 1:5 to 100 (preferably 1:10), the core microporous molecular sieve is stirred and mixed with water to form a mixture A; EO ₂₀ PO ₇₀ EO ₂₀ (P123) is a template, according to EO ₂₀ PO ₇₀ EO ₂₀ :MO _n/2 :SiO ₂ :Inorganic acid:H ₂ O=1:0.1～40:40～150:80～800 :5000～18000 (preferably 1:1.3～25.8:62.5～125.3:100～500:8000～15000) material ratio, mix a certain amount of EO ₂₀ PO ₇₀ EO ₂₀ , H ₂ O and inorganic acid evenly , adding the precursor of element M and silicon source, stirring and mixing uniformly to form mixture B; the H ₂ O or water is distilled water or deionized water, adding mixture A to mixture B, stirring and mixing uniformly, at 10 Crystallization reaction at ~200°C for 0-72 hours, filtering and washing to obtain the crystallized product, then drying and roasting the crystallized product at 450-600°C for 2-30 hours to remove the template agent to obtain the core-shell Type composite molecular sieve catalyst; the silicon source is silica sol, ethyl orthosilicate or methyl orthosilicate; the n is the number of valence electrons of the substituting element M;

The substituting element M is the following one or a mixture of two or more in any proportion: (1) beryllium, (2) magnesium, (3) calcium, (4) strontium, (5) boron, (6) aluminum, (7) ) gallium, (8) manganese, (9) iron, (10) cobalt, (11) nickel, (12) copper, (13) zinc, (14) titanium, (15) vanadium, (16) chromium, (17) ) germanium, (18) zirconium, (19) niobium, (20) molybdenum, (21) tin or (22) tungsten;

The core microporous molecular sieve is a mixture of one or more of the following in any proportion: (1) HZSM-5 molecular sieve, (2) HY molecular sieve, (3) Hβ molecular sieve, (4) HUSY molecular sieve, (5) HMOR molecular sieve , (6) HMCM-22 molecular sieve; the dosage of the core microporous molecular sieve accounts for 0.1-50.0% of the mass fraction of the core-shell composite molecular sieve catalyst; the silicon-aluminum molar ratio of the various types of core microporous molecular sieves is the most preferred HZSM-5 (its n(SiO ₂ )/n(Al ₂ O ₃ )=38), Hβ (its n(SiO ₂ )/n(Al ₂ O ₃ )=30), HY (its n(SiO _{2 )} )/n(Al ₂ O ₃ )=9.6), HUSY (with n(SiO ₂ )/n(Al ₂ O ₃ )=10), HMOR (with n(SiO ₂ )/n(Al ₂ O ₃ )= 23), HMCM-22 (n(SiO ₂ )/n(Al ₂ O ₃ )=28.5).

The modified compound is a mixture of one or more of the following in any proportion: (1) phosphoric acid, (2) hydrofluoric acid, (3) ammonium fluoride, (4) phosphotungstic heteropoly acid, (5) silicon Tungsten heteropoly acid, (6) phosphomolybdenum heteropoly acid, (7) phosphotungstic heteropoly acid cesium salt, (8) silicotungstic heteropoly acid cesium salt, (9) phosphomolybdenum heteropoly acid cesium salt, (10) Aluminum chloride, (11) zinc chloride, (12) ferric chloride, (13) copper chloride, (14) chromium chloride, (15) boric acid; The mass of molecular sieve is 0.01-60wt%.

The mineral acid is preferably one of the following: hydrochloric acid, nitric acid or sulfuric acid.

The precursors of the substituting element M are oxides, acids, hydroxides or salts.

When the M is Al, the precursor of M is: aluminum isopropoxide, boehmite, pseudoboehmite, alumina monohydrate, aluminum nitrate, aluminum sol, aluminum gel or aluminum sulfate.

The composite solid acid catalyst is prepared as follows: calculate the dosage of the modified compound according to the load of the modified compound, impregnate the core-shell type composite molecular sieve with a solution obtained by dissolving the modified compound in a solvent, and then dry, or/and roasting to obtain a composite solid acid catalyst with a modified compound loading of 0.01-60wt%; the solvent is one of the following: water, acetone, carbon tetrachloride or absolute ethanol.

Further, it is preferred that the reaction temperature is 100-300°C, the pressure is 0.2-4.0MPa, the total mass space velocity of the feed is 0.5-10.0 hours- ¹ , and the most preferred is the reaction temperature 180-220°C, the pressure The mass space velocity is 0.5 to 2.0 hours ^-1 .

The aromatics are aromatics generated by a reforming unit and aromatics generated by a steam cracking unit.

Further, the aromatics are benzene, toluene or xylene after separation of aromatics generated by a reforming unit or a steam cracking unit, and the separation method is a method well known to those skilled in the art, usually a distillation separation method.

The refining method of the present invention also includes aromatic hydrocarbon pretreatment. The aromatic hydrocarbon pretreatment is that the aromatic hydrocarbon is adsorbed by the adsorbent bed and then contacted with a solid acid catalyst to carry out the deolefination reaction; the adsorption pretreatment condition is: temperature 0～ 200°C, pressure 0.1-6.0MPa, mass space velocity 0.2-15 hours ^-1 , the adsorbent is a mixture of one or more of the following in any proportion: 13X molecular sieve, HY molecular sieve, activated clay, activated carbon, HUSY molecular sieve or acidic ion exchange resin.

The reaction in the aromatics refining method is carried out in two or more reactors connected in series or in parallel.

The reactors used in the reaction can be selected from fixed bed, expanded bed, fluidized bed, stirred tank reactor, and catalytic distillation reactor. The reaction unit can have multiple reactors operating in parallel or in series. The fluid in the reactor can adopt upward flow or downward flow.

In the refining process of aromatics, two reactors can be operated in series, the first reactor is used as a pretreatment reactor, and the second reactor is used as a refining reactor. During the reaction, when the content of refined aromatics and olefins in the second reactor exceeds the standard, such as its bromine index is greater than 100mgBr/100g, switch the second reactor to the first reactor; Exceeding the standard, if the bromine index is greater than 300mgBr/100g, regenerate the catalyst in the first reactor. One of the regeneration methods is to stop the aromatics, and use polar solvents such as methanol, ethanol, acetone, methylene chloride, carbon tetrachloride, polyethylene glycol, diethylene glycol, triethylene glycol, tetrahydrofuran, benzoic acid, phenol, etc. The active catalyst is washed and regenerated; the second regeneration method is to regenerate the deactivated catalyst with an oxygen-containing gas; the third regeneration method is to wash and regenerate the deactivated catalyst with an oxygen-containing gas first, and then regenerate the deactivated catalyst with an oxygen-containing gas .

The beneficial effects of a method for removing trace olefins in aromatics of the present invention are mainly reflected in:

(1) The process flow is simple, no hydrogen is consumed, and the device investment and operation costs are low;

(2) The catalyst has good activity and stability, the stable operation time of the device is long, and the loss of aromatics is small, which can avoid frequent switching operations of reactor reaction and regeneration;

(3) The catalyst can be regenerated, which can avoid landfill disposal of a large number of spent catalysts, and has little impact on the environment.

(4) Specific implementation methods

The present invention is further described below in conjunction with specific embodiment, but protection scope of the present invention is not limited thereto:

The triblock polymer P123 used in the examples comes from Aldrich Company, and the alumina monohydrate comes from Shandong Aluminum Group Company; the microporous molecular sieve HZSM-5 (its n(SiO ₂ )/n(Al ₂ O ₃ )= 38), Hβ (n(SiO ₂ )/n(Al ₂ O ₃ )=30) from Nankai University Catalyst Factory, HY (n(SiO ₂ )/n(Al ₂ O ₃ )=9.6) and HUSY (with n(SiO ₂ )/n(Al ₂ O ₃ )=10) from Wenzhou Huahua Group Company, HMOR (with n(SiO ₂ )/n(Al ₂ O ₃ )=23) from Jiangsu Aoke Petrochemical Technology Co., Ltd., HMCM-22 (with n(SiO ₂ )/n(Al ₂ O ₃ )=28.5) comes from Jiangyan Chemical Auxiliary Factory.

The catalyst extrusion molding process is to mix 30 grams of synthetic M-SBA-15 mesoporous/microporous composite molecular sieve powder with 9 grams of alumina monohydrate and 0.75 gram of turnip powder, add 36 grams of distilled water and 55 grams of mass content of 10% nitric acid aqueous solution, kneaded into mud balls, extruded into strips, dried and then heated to 550°C for 4 hours.

comparative example

Synthesis of Al-SBA-15 Mesoporous Molecular Sieve Catalyst

According to the calculation of the molar ratio of raw materials P123:Al ₂ O ₃ :SiO ₂ :HCl:H ₂ O is 1:3.1:62.5:300:10000, weigh 20 grams of P123, mix it with the calculated amount of distilled water and hydrochloric acid, and heat it at 40°C Stir and mix at high temperature for 1.0 hour, add 1.3 g of alumina monohydrate and continue to stir and mix for 1.0 hour; then, add 45.0 g of tetraethyl orthosilicate and continue to stir and mix for 5.0 hours to obtain a mixed slurry. The mixed slurry was placed in a plastic container, crystallized at 100°C and autogenous pressure for 48 hours, filtered, washed and dried, and fired at 550°C for 5.0 hours to remove the template agent to obtain Al-SBA-15 13.8 grams of mesoporous molecular sieve catalyst powder. Mix 10 grams of the catalyst powder with 3 grams of alumina monohydrate and 0.25 grams of scallop powder, add 12 grams of distilled water and 18.3 grams of 10% nitric acid aqueous solution, knead into a mud ball, extrude into strips, and dry The temperature was programmed to rise to 550°C for 4 hours, and then crushed to obtain catalyst particles of 20-40 mesh, which were designated as CAT-0. The catalyst was used in the deolefination reaction experiment of aromatic hydrocarbons, and the results of the reaction experiment are shown in Table 3.

Example 1:

Synthesis of Al-SBA-15 Mesoporous/Hβ Microporous Composite Molecular Sieve Catalyst

5 g of Hβ microporous molecular sieve powder was used as the inner core, and stirred and mixed with 50 g of distilled water for 1.0 hour to obtain a mixture A. According to the calculation of the molar ratio of raw materials P123:Al ₂ O ₃ :SiO ₂ :HCl:H ₂ O is 1:3.1:62.5:300:10000, weigh 20 grams of P123, mix it with the calculated amount of distilled water and hydrochloric acid, and heat it at 40°C Stir and mix at high temperature for 1.0 hour, add 1.3 g of alumina monohydrate and continue to stir and mix for 1.0 hour; add 45.0 g of ethyl orthosilicate while stirring to obtain mixture B. Then, the mixture A was added to the mixture B, and the mixture was stirred and mixed at a temperature of 40° C. for 5.0 hours to obtain a mixed slurry. The mixed slurry was placed in a plastic container, crystallized at 100°C and autogenous pressure for 48 hours, filtered, washed, and dried, and fired at 550°C for 5.0 hours to remove the template agent to obtain the inner core microporous molecular sieve 18.7 grams of Al-SBA-15 mesoporous/Hβ microporous core-shell composite molecular sieve catalyst powder with a total catalyst mass of 27.8% was extruded and crushed to obtain 20-40 mesh catalyst particles, which were designated as CAT-1.

Embodiment 2～6:

Using the same synthesis method as in Example 1, the difference is that HZSM-5 molecular sieves, HY molecular sieves, HUSY molecular sieves, HMOR molecular sieves, and HMCM-22 molecular sieves are used as cores, and the core microporous molecular sieves are obtained through hydrothermal synthesis and extrusion molding. The Al-SBA-15 mesoporous/microporous core-shell composite molecular sieve catalyst, which accounts for 27.8% of the total mass of the catalyst, is listed in Table 1.

Table 1

Embodiment 7～25:

Using the same synthesis method as in Example 1, the difference is that the three-block polymer P123 is used as a template, and butyl titanate, cobalt nitrate, zinc nitrate, gallium nitrate, manganese nitrate, strontium nitrate, zirconium nitrate, nitric acid Calcium, beryllium nitrate, iron nitrate, nickel nitrate, vanadium nitrate, chromium nitrate, germanium nitrate, tin nitrate, molybdenum nitrate, niobic acid, copper nitrate, tungstic acid as the precursor of the substitution element M, according to P123:MO _n/2 : SiO ₂ :HCl:H ₂ O is 1:6.25:62.5:300:10000 molar ratio of raw materials to synthesize M-SBA-15 molecular sieve powder containing substituting elements, and then extruded and crushed to obtain 20-40 mesh catalyst particles , listed in Table 2.

Table 2

Example 26:

Synthesis of B-Mg-SBA-15 Mesoporous/Hβ Microporous Composite Molecular Sieve Catalyst

5 g of Hβ microporous molecular sieve powder was mixed with 50 g of distilled water for 1.0 hour to obtain mixture A. According to the calculation of the molar ratio of raw materials P123:B ₂ O ₃ :MgO:SiO ₂ :HCl:H ₂ O is 1:3.1:6.5:62.5:350:11000, weigh 20 grams of P123 and mix it with the calculated amount of distilled water and hydrochloric acid , stirred and mixed at 40° C. for 1.0 hour, added the calculated amount of boric acid, and continued to stir and mixed for 1.0 hour; Then, the mixture A was added to the mixture B, and the mixture was stirred and mixed at a temperature of 40° C. for 5.0 hours to obtain a mixed slurry. The mixed slurry was placed in a plastic container, crystallized at 60°C and autogenous pressure for 12 hours, filtered, washed, and dried, and fired at 550°C for 5.0 hours to remove the template agent to obtain the inner core microporous molecular sieve B-Mg-SBA-15 mesoporous/Hβ microporous core-shell type composite molecular sieve catalyst powder with 26.3% of the total catalyst mass was extruded and crushed to obtain 20-40 mesh catalyst particles, which were designated as CAT-26.

Embodiment 27～41:

Preparation of composite solid acid catalyst by loading and modifying the Al-SBA-15 mesoporous/Hβ microporous composite molecular sieve catalyst of Example 1

The 20-40 mesh Al-SBA-15 mesoporous/Hβ microporous composite molecular sieve particles prepared in Example 1 were used in the following operations (1)-(14) to prepare supported catalysts:

(1) 10 grams of the Al-SBA-15 mesoporous/Hβ microporous composite molecular sieve obtained in Example 1 was impregnated with 100 ml of phosphoric acid aqueous solution with a concentration of 0.143 mol/L for 24 hours at room temperature, followed by drying at 110°C for 3 hours Calcined at 400°C for 3 hours to obtain a P/Al-SBA-15/Hβ composite solid acid catalyst with a P ₂ O ₅ loading of 10.0 wt%, which was designated as CAT-27 catalyst (Example 27).

(2) Dissolve 5.0 grams of boric acid in 30 grams of acetone solvent, dissolve evenly, add 10 grams of the Al-SBA-15 mesoporous/Hβ microporous composite molecular sieve obtained in Example 1, stir at room temperature for 15 minutes, and heat to evaporate Acetone was dried at 120°C for 3 hours to obtain a B/Al-SBA-15/Hβ composite solid acid catalyst with a boric acid loading of 50 wt%, which was designated as CAT-28 catalyst (Example 28).

(3) 10 grams of the Al-SBA-15 mesoporous/Hβ microporous composite molecular sieve obtained in Example 1 was impregnated with 100 ml of hydrofluoric acid aqueous solution with a concentration of 0.167 mol/L for 24 hours at room temperature, followed by drying at 110°C After 3 hours and 200°C calcination treatment for 3 hours, a F/Al-SBA-15/Hβ composite solid acid catalyst with a F loading of 3.0wt% was obtained, which was designated as CAT-29 catalyst (Example 29).

(4) According to the method of Example 29, a modified NH ₄ F/Al-SBA-15/Hβ composite solid acid catalyst with a loaded ammonium fluoride loading of 3.0 wt% was prepared, denoted as CAT-30 (Example 30).

(5) Prepare PW ₁₂ /Al-SBA-15/Hβ composite solid acid catalyst loaded with phosphotungstic heteropolyacid (Shanghai Chemical Reagent Company) by using phosphotungstic heteropolyacid. The phosphotungstic heteropolyacid aqueous solution of 0.008mol/L with 100 milliliters of concentration is carried out room temperature impregnation treatment 24 hours to the Al-SBA-15 mesoporous/Hβ microporous composite molecular sieve that 10 grams of embodiment 1 gains, then carry out 110 ℃ of drying 3 hour and 200°C for 3 hours to obtain a PW ₁₂ /Al-SBA-15/Hβ composite solid acid catalyst with a PW ₁₂ loading of 20 wt%, which is designated as CAT-31 (Example 31).

(6) SiW _{12 /Al-SBA-15/Hβ composite solid acid catalyst loaded with silicotungstic heteropoly acid (Shenyang Chengsheng Reagent Factory) was used to prepare SiW 12} /Al-SBA-15/Hβ composite solid acid catalyst. With 100 milliliters of concentrations of 0.013mol/L silicotungstic heteropoly acid aqueous solution, 10 grams of Al-SBA-15 mesoporous/Hβ microporous composite molecular sieves obtained in Example 1 were impregnated at room temperature for 24 hours, followed by drying at 110°C for 3 hour and 200°C for 3 hours, and a SiW ₁₂ /Al-SBA-15/Hβ composite solid acid catalyst with a SiW ₁₂ loading of 30wt% was obtained, which was designated as CAT-32 (Example 32).

(7) PMo ₁₂ /Al-SBA-15/Hβ composite solid acid catalyst modified by phosphomolybdenum heteropoly acid (Shenyang Xinxing Reagent Factory) was prepared. With 100 milliliters of concentrations being 0.025mol/L phosphomolybdenum heteropolyacid aqueous solution, the Al-SBA-15 mesoporous/Hβ microporous composite molecular sieve that 10 grams of embodiment 1 gains is carried out room temperature immersion treatment 24 hours, then carries out 110 ℃ of drying 3 hour and 200°C for 3 hours to obtain a PMo ₁₂ /Al-SBA-15/Hβ composite solid acid catalyst with a PMo ₁₂ loading of 30 wt%, which is designated as CAT-33 (Example 33).

(8) Preparation of Cs _2.5 H _0.5 PW ₁₂ /Al-SBA-15/Hβ composite solid acid catalyst modified by cesium salt of phosphotungstic acid.

0.48 g of Cs ₂ CO ₃ and 3.49 g of H ₃ PW ₁₂ O ₄₀ ·6H ₂ O were formulated into 0.1 mol/L and 0.08 mol/L aqueous solutions, respectively. First, add 10 grams of Al-SBA-15/Hβ composite molecular sieve to the cesium carbonate aqueous solution, stir at room temperature for 3 hours, evaporate the moisture at 80°C, and roast at 500°C for 3 hours; Mix tungstic acid aqueous solution, stir at room temperature for 12 hours, evaporate water at 80°C, dry at 120°C for 5 hours, and roast at 200°C for 2 hours to obtain Cs _2.5 H _0.5 PW ₁₂ with a loading capacity of 30wt% The Cs _2.5 H _0.5 PW ₁₂ /Al-SBA-15/Hβ composite solid acid catalyst is designated as CAT-34 (Example 34).

(9) Preparation of Cs _2.5 H _0.5 SiW ₁₂ /Al-SBA-15/Hβ composite solid acid catalyst supported by cesium salt of silicotungstic heteropolyacid.

0.48 g of Cs ₂ CO ₃ and 3.49 g of H ₃ SiW ₁₂ O ₄₀ ·6H ₂ O were formulated into 0.1 mol/L and 0.08 mol/L aqueous solutions, respectively. First, add 10 grams of Al-SBA-15/Hβ composite molecular sieve to the cesium carbonate aqueous solution, stir at room temperature for 3 hours, evaporate the moisture at 80°C, and roast at 500°C for 3 hours; Mix tungstic acid aqueous solution, stir at room temperature for 12 hours, evaporate to dryness at 80°C, dry at 120°C for 5 hours, and roast at 200°C for 2 hours to obtain Cs _2.5 H _0.5 SiW ₁₂ with a loading capacity of 30wt% The Cs _2.5 H _0.5 SiW ₁₂ /Al-SBA-15/Hβ composite solid acid catalyst is designated as CAT-35 (Example 35).

(10) Preparation of modified Cs _2.5 H _0.5 PMo ₁₂ /Al-SBA-15/Hβ composite solid acid catalyst loaded with cesium salt of phosphomolybdenum heteropolyacid.

0.81 g of Cs ₂ CO ₃ and 3.83 g of H ₃ PMo ₁₂ O ₄₀ ·6H ₂ O were formulated into 0.1 mol/L and 0.08 mol/L aqueous solutions, respectively. First, add 10 grams of Al-SBA-15/Hβ composite molecular sieve to the cesium carbonate aqueous solution, stir at room temperature for 3 hours, evaporate the moisture at 80°C, and roast at 500°C for 3 hours; then the roasted sample is mixed with phosphorus Molybdic acid aqueous solution was mixed, stirred at room temperature for 12 hours, evaporated to dryness at 80°C, dried at 120°C for 5 hours, and calcined at 200°C for 2 hours to obtain Cs _2.5 H _0.5 PMo ₁₂ with a loading capacity of 30wt% The Cs _2.5 H _0.5 PMo ₁₂ /Al-SBA-15/Hβ composite solid acid catalyst is designated as CAT-36 (Example 36).

(11) Preparation of aluminum chloride-supported modified AlCl ₃ /Al-SBA-15 /Hβ composite solid acid catalyst.

The Al-SBA-15/Hβ composite molecular sieve that 10 grams of embodiment 1 gained and 250 milliliters of dry CCl ₄ are added in the there-necked flask of 500 milliliters, oil bath heating reflux 1.5 hours, then add 2 grams of aluminum chloride, continue heating Refluxed for 3 hours; filtered and washed twice with hot _CCl4 , the resulting solid was dried at 120°C for 5 hours to obtain _AlCl3 /Al-SBA-15/Hβ composite solid acid with a loading of aluminum chloride of 20wt% Catalyst, designated CAT-37 (Example 37).

(12) According to the method of Example 37, prepare a loaded modified ZnCl ₂ /Al-SBA-15/Hβ composite solid acid catalyst with a zinc chloride loading of 20wt%, denoted as CAT-38 (Example 38) .

(13) According to the method in Example 37, prepare a loaded modified FeCl ₃ /Al-SBA-15/Hβ composite solid acid catalyst with a ferric chloride loading of 20 wt%, which is designated as CAT-39 (Example 39) .

(14) According to the method of Example 37, a modified CuCl ₂ /Al-SBA-15/Hβ composite solid acid catalyst with a copper chloride loading of 20 wt% was prepared, denoted as CAT-40 (Example 40) .

(15) According to the method in Example 37, prepare a loaded modified CrCl ₂ /Al-SBA-15/Hβ composite solid acid catalyst with a loading capacity of chromium chloride of 20 wt%, denoted as CAT-41 (Example 41) .

Example 42:

Synthesis of Al-SBA-15 Mesoporous/Hβ Microporous Composite Molecular Sieve Catalyst with Nitric Acid

0.4 g of Hβ microporous molecular sieve powder was used as the inner core, and stirred and mixed with 50 g of distilled water for 1.0 hour to obtain a mixture A. Calculate according to the raw material molar ratio P123:Al ₂ O ₃ :SiO ₂ :HNO ₃ :H ₂ O is 1:25.8:125.3:500:15000, weigh 20 grams of P123, mix it with the calculated amount of distilled water and nitric acid, and mix it at 40 Stir and mix at ℃ for 1.0 hour, add the calculated amount of aluminum nitrate and continue to stir and mix for 1.0 hour; Then, the mixture A was added to the mixture B, and the mixture was stirred and mixed at a temperature of 40° C. for 5.0 hours to obtain a mixed slurry. The mixed slurry was placed in a plastic container, crystallized at 100°C and autogenous pressure for 72 hours, filtered, washed and dried, and fired at 550°C for 5.0 hours to remove the template agent to obtain the inner core microporous molecular sieve Al-SBA-15 mesoporous/Hβ microporous core-shell composite molecular sieve catalyst powder with a total mass of 1.4% of the catalyst was extruded and crushed to obtain 20-40 mesh catalyst particles, which were designated as CAT-42.

Example 43:

Synthesis of Al-SBA-15 Mesoporous/Hβ Microporous Composite Molecular Sieve Catalyst with Sulfuric Acid

12.2 g of Hβ microporous molecular sieve powder was used as the inner core, and stirred and mixed with 50 g of distilled water for 1.0 hour to obtain a mixture A. According to the calculation of the molar ratio of raw materials P123:Al ₂ O ₃ :SiO ₂ :H ₂ SO ₄ :H ₂ O is 1:1.3:76.5:100:8000, weigh 20 grams of P123, mix it with the calculated amount of distilled water and sulfuric acid, Stir and mix at 40° C. for 1.0 hour, add the calculated amount of alumina monohydrate and continue to stir and mix for 1.0 hour; Then, add mixture A to mixture B, continue to stir and mix at 40°C for 5.0 hours to obtain a mixed slurry; after filtering, washing, and drying, bake at 550°C for 5.0 hours to remove the templating agent and obtain inner core micropores The Al-SBA-15 mesoporous/Hβ microporous core-shell type composite molecular sieve catalyst powder whose molecular sieve accounts for 42.1% of the total mass of the catalyst is extruded and crushed to obtain 20-40 mesh catalyst particles, which are designated as CAT-43.

Embodiment 44～86:

Aromatics removal of olefins using a solid acid catalyst.

A fixed-bed reaction device was adopted, and the reactor was a stainless steel tube with a length of 100 cm and an inner diameter of 1.0 cm. 5.0 grams of catalyst was packed in the middle of the reactor, and both ends of the reactor were filled with quartz sand. Under the conditions of pressure 1.0MPa, temperature 180°C, and mass space velocity 2.0h ^-1 , a continuous olefin removal experiment was carried out on the reformed aromatics of a petrochemical enterprise. The RPA-100Br type produced by Jiangsu Jianghuan Analytical Instrument Co., Ltd. The bromine index measuring instrument measures the bromine index of the reaction raw material and the refined product. The measurement result of the bromine index of the aromatic hydrocarbon raw material is 865.5mgBr/100g, and the experimental results of the bromine index of the refined product are listed in Table 3.

Comparing the data in Table 3, it can be seen that the catalyst CAT-0 coreless microporous molecular sieve prepared in the comparative example has a lower catalytic activity, resulting in a higher bromine index of the aromatics refined product.

table 3

Example 87:

The effect of reaction temperature on the removal of olefins from aromatics was investigated.

A fixed bed reaction device was adopted, and the reactor was a stainless steel tube with a length of 100 cm and an inner diameter of 1.0 cm. 5.0 grams of the CAT-1 catalyst prepared in Example 1 was packed in the middle of the reactor, and both ends of the reactor were filled with quartz sand. Under the conditions of pressure 3.0MPa and mass space velocity 2.0h ^-1 , the reaction experiment of removing olefins from reformed aromatics in a petrochemical enterprise was carried out, and the bromine index of the reaction raw materials and refined products was measured with the RPA-100Br bromine index tester. The measurement result of the bromine index of the aromatic hydrocarbon raw material is 865.5mgBr/100g, and the measurement results of the bromine index of the refined products at different temperatures are listed in Table 4. From the data in Table 4, it can be seen that the deolefination rate increases with the increase of the reaction temperature, which shows that an appropriate increase in the reaction temperature is beneficial to the deolefination of aromatic hydrocarbons.

Table 4

Example 88:

The effect of mass space velocity on the removal of olefins from aromatics was investigated.

A fixed bed reaction device was adopted, and the reactor was a stainless steel tube with a length of 100 cm and an inner diameter of 1.0 cm. 5.0 grams of the CAT-1 catalyst prepared in Example 1 was packed in the middle of the reactor, and both ends of the reactor were filled with quartz sand. Under the conditions of pressure 1.5MPa and temperature 180°C, the reaction experiment of removing olefins from reformed aromatics in a petrochemical enterprise was carried out, and the bromine index of the reaction raw materials and refined products was measured with the RPA-100Br bromine index tester. The measurement result of the index is 865.5mgBr/100g, and the measurement results of the bromine index of the refined products with different mass space velocities are listed in Table 5. It can be seen from the data in Table 5 that the deolefination rate increases with the decrease of the mass space velocity, which shows that a proper reduction of the mass space velocity is beneficial to increase the deolefination rate of aromatics.

table 5

Example 89:

Aromatics undergo a cascade operation of adsorption pretreatment and catalytic deolefination reaction.

Activated clay produced by Fushun Petrochemical Company, HY molecular sieve produced by Wenzhou Huahua Group Co., Ltd., 13X molecular sieve and activated carbon produced by Shanghai Sinopharm Chemical Reagent Co., Ltd., and D005 acidic ion exchange resin produced by Dandong Mingzhu Special Resin Co., Ltd. were used as adsorbents. . Two fixed-bed reactors are connected in series, the first reactor is used as an adsorption treatment bed, and the second reactor is used as a catalyst bed. 10.0 grams of adsorbent and 5.0 grams of catalyst CAT-1 were loaded in the first and second reactors respectively, and both ends of the two reactors were filled with quartz sand. Under the conditions of pressure 1.0MPa, first reactor temperature 50°C, second reactor temperature 180°C, reformed aromatics feed rate 5.0g/h, the reaction experiment of continuous aromatics removal of olefins was carried out, and the bromine index of aromatics raw materials The measurement result of Br is 865.5mgBr/100g, and the bromine index measurement results of refined products with different duration of reaction are listed in Table 6.

Table 6

It can be seen from the data in Table 6 that after 100 days of continuous aromatics deolefination reaction, the bromine index of refined aromatics is less than 40 mgBr/100g, and the deolefination rate is always above 95.0%, indicating that the catalyst has good activity and stability under this operating condition.

Example 90:

Aromatics were subjected to a series operation of adsorption pretreatment and catalytic deolefination reaction under different conditions.

Using 13X molecular sieve from Shanghai Sinopharm Chemical Reagent Co., Ltd. as the adsorbent, two fixed-bed reactors were connected in series, the first reactor was used as an adsorption treatment bed, and the second reactor was used as a catalyst bed, and the adsorbent and catalyst were respectively CAT-1 is loaded in the first and second reactors, both ends of which are filled with quartz sand. Under the conditions of pressure 6.0MPa, first reactor temperature 10-200°C and mass space velocity 0.2-15 hours- ¹ , second reactor temperature 180°C and mass space velocity 1.0 hours ^-1 , carry out reforming aromatics removal In the olefin removal reaction experiment, the bromine index of the aromatic raw material was 865.5 mgBr/100g. The results of the bromine index measurement of the refined product of the adsorption pretreatment under different conditions and the catalytic de-olefin reaction under certain conditions are listed in Table 7.

Table 7

From the data in Table 7, it can be seen that the bromine index of the refined aromatics gradually decreases with the increase of the adsorption temperature or the decrease of the adsorption mass space velocity after the adsorption pretreatment under different conditions and the catalytic deolefination reaction under certain conditions are operated in series. The effect of olefins gradually increased, indicating that appropriately increasing the adsorption temperature or reducing the space velocity of the adsorption mass was beneficial to improving the refining effect of aromatics.

Example 91:

Aromatics removal of olefins using a two-reactor series reaction unit.

5.0 grams of catalyst CAT-1 and 5.0 grams of catalyst CAT-4 were packed in the middle of the first reactor and the second reactor respectively, and both ends of the two reactors were filled with quartz sand. Under the conditions of pressure 1.0MPa, temperature of the first reactor 100°C, temperature of the second reactor 180°C, and feed rate of reformed aromatics 10.0g/h, the reaction experiment of continuous aromatics removal of olefins was carried out, and the bromine index of aromatics raw materials The determination result of Br is 865.5mgBr/100g, and the determination results of the bromine index of refined products with different duration of reaction are listed in Table 8. A 1790 gas chromatograph equipped with a 50-meter OV-101 capillary column and FID detector produced by Agilent Technologies Shanghai Analytical Instrument Co., Ltd. was used to analyze the composition of aromatic hydrocarbon raw materials and refined products. The results are shown in Table 9.

Table 8

From the data in Table 8, it can be seen that after 100 days of continuous aromatics deolefination reaction, the deolefination rate is always above 96.0%, indicating that the catalyst has good activity stability under this operating condition, and the stable operation time of the device is long.

Table 9

It can be seen from Table 9 that the product composition of the aromatic product treated with the catalyst is basically the same as that of the raw material, and there is basically no change in the composition of the aromatic product, indicating that the catalyst can meet the product quality requirements of industrial production.

Example 92:

The reaction experiment of benzene to remove olefins was carried out.

A fixed-bed reaction device was used, and 5.0 grams of the CAT-1 catalyst prepared in Example 1 was packed in the middle of the reactor, and both ends of the reactor were filled with quartz sand. Under the conditions of pressure 2.5MPa, temperature 200℃, and mass space velocity 2.0h ^-1 , the benzene obtained by distillation and separation of reformed mixed aromatics in a petrochemical enterprise was tested for the removal of olefins, and the bromine index was determined by RPA-100Br The bromine index of the reaction raw material and the refined product was measured by an instrument. The measurement result of the benzene bromine index of the raw material was 348.6mgBr/100g. After 90 days of continuous reaction, the measurement result of the refined benzene bromine index was less than 38.0mgBr/100g.

Example 93:

The reaction experiment of steam cracking aromatics to remove olefins was carried out.

A fixed-bed reaction device was used, and 5.0 grams of the CAT-1 catalyst prepared in Example 1 was packed in the middle of the reactor, and both ends of the reactor were filled with quartz sand. Under the conditions of pressure 2.0MPa, temperature 220℃, and mass space velocity 2.0h ^-1 , the reaction experiment of removing olefins from steam cracking aromatics in a petrochemical enterprise was carried out, and the reaction raw materials and refined The bromine index of the product is 1127.5mgBr/100g as the raw material aromatic hydrocarbon. After 90 days of reaction, the bromine index of the refined steam cracking aromatic hydrocarbon is less than 81.0mgBr/100g.

The above shows that the catalyst provided by the invention has high catalytic activity, reaction selectivity and activity stability, and the method for removing trace olefins in aromatics provided by the invention has a good application prospect.

Claims (10)

1. A method for refining aromatic hydrocarbons, characterized in that the method is: under the conditions of temperature 50-400°C, pressure 0.1-12MPa, feed quality space velocity 0.1-15 hours ^-1 , aromatic hydrocarbons and solid acid Catalyst contact reaction to obtain refined aromatic hydrocarbons; the solid acid catalyst is a core-shell composite molecular sieve catalyst with a shell wrapped around the core or a composite solid acid catalyst obtained by loading a modified compound on a core-shell composite molecular sieve catalyst. The layer is M-SBA-15 mesoporous molecular sieve containing substituting element M, and the inner core is microporous molecular sieve; The core-shell composite molecular sieve catalyst is prepared as follows: according to the solid-to-liquid mass ratio of 1:5-100, the core microporous molecular sieve is stirred and mixed with water to form a mixture A; the tri-block polymer EO ₂₀ PO ₇₀ EO ₂₀ is a template agent, formulated according to the amount of EO ₂₀ PO ₇₀ EO ₂₀ :MO _n/2 :SiO ₂ :Inorganic acid:H ₂ O=1:0.1～40:40～150:80～800:5000～18000 Ratio, mix a certain amount of EO ₂₀ PO ₇₀ EO ₂₀ , H ₂ O, and inorganic acid uniformly, add the precursor of the substitution element M and the silicon source, stir and mix uniformly to form a mixture B; the H ₂ O or water is Distilled water or deionized water, add mixture A to mixture B, stir and mix evenly, crystallize at 10-200°C for 0-72 hours, filter and wash to obtain a crystallized product, and then pass the crystallized product through Drying and roasting treatment to remove the template agent to obtain the core-shell composite molecular sieve catalyst; the silicon source is silica sol, ethyl orthosilicate or methyl orthosilicate; the n is the number of valence electrons of the substituting element M ; The substituting element M is the following one or a mixture of two or more in any proportion: (1) beryllium, (2) magnesium, (3) calcium, (4) strontium, (5) boron, (6) aluminum, (7) ) gallium, (8) manganese, (9) iron, (10) cobalt, (11) nickel, (12) copper, (13) zinc, (14) titanium, (15) vanadium, (16) chromium, (17) ) germanium, (18) zirconium, (19) niobium, (20) molybdenum, (21) tin or (22) tungsten; The core microporous molecular sieve is a mixture of one or more of the following in any proportion: (1) HZSM-5 molecular sieve, (2) HY molecular sieve, (3) Hβ molecular sieve, (4) HUSY molecular sieve, (5) HMOR molecular sieve Or (6) HMCM-22 molecular sieve; the dosage of the core microporous molecular sieve accounts for 0.1-50.0% of the mass fraction of the core-shell composite molecular sieve catalyst; The modified compound is a mixture of one or more of the following in any proportion: (1) phosphoric acid, (2) hydrofluoric acid, (3) ammonium fluoride, (4) phosphotungstic heteropoly acid, (5) silicon Tungsten heteropoly acid, (6) phosphomolybdenum heteropoly acid, (7) cesium salt of phosphotungstic heteropoly acid, (8) cesium salt of silicotungstic heteropoly acid, (9) cesium salt of phosphomolybdenum heteropoly acid, (10) Aluminum chloride, (11) zinc chloride, (12) ferric chloride, (13) copper chloride, (14) chromium chloride or (15) boric acid; The mass of molecular sieve is 0.01-60wt%. 2. The method for refining aromatics as claimed in claim 1, characterized in that said inorganic acid is one of the following: hydrochloric acid, nitric acid or sulfuric acid. 3. The method for refining aromatic hydrocarbons according to claim 1, characterized in that the precursor of the substituting element M is an oxide, an acid, a hydroxide or a salt. 4. The method for refining aromatic hydrocarbons as claimed in claim 3, wherein when said M is Al, the precursor of said M is: aluminum isopropoxide, boehmite, pseudo-boehmite, alumina monohydrate , aluminum nitrate, aluminum sol, aluminum gel or aluminum sulfate. 5. The method for refining aromatic hydrocarbons as claimed in claim 1, characterized in that said composite solid acid catalyst is prepared as follows: calculate the amount of modified compound according to the loading capacity of modified compound, and dissolve the modified compound in a solvent to obtain The core-shell type composite molecular sieve is impregnated with the solution, and then dried, or/and roasted to obtain a composite solid acid catalyst with a modified compound loading of 0.01-60wt%; the solvent is one of the following: water , acetone, carbon tetrachloride or absolute ethanol. 6 . The method for refining aromatics according to claim 1 , characterized in that the reaction temperature is 100-300° C., the pressure is 0.2-4.0 MPa, and the total mass space velocity of the feed is 0.5-10.0 hours ⁻¹ . 7. The method for refining aromatics according to claim 1, wherein the aromatics are aromatics generated by a reforming unit or aromatics generated by a steam cracking unit. 8. The method for refining aromatics as claimed in claim 1, characterized in that said aromatics are benzene, toluene or xylene after the separation of aromatics generated by a reforming unit or a steam cracking unit. 9. The method for refining aromatics as claimed in claim 1, characterized in that said refining method also includes aromatics pretreatment, said aromatics pretreatment is that the aromatics are contacted with a solid acid catalyst to react after being adsorbed by the adsorbent bed; The adsorption pretreatment conditions are: temperature 0-200°C, pressure 0.1-6.0MPa, mass space velocity 0.2-15 hours ^-1 , and the adsorbent is a mixture of one or more of the following in any proportion: 13X molecular sieve, HY molecular sieve, activated clay, activated carbon, HUSY molecular sieve or acidic ion exchange resin. 10. The method for refining aromatics as claimed in claim 1, characterized in that said reaction is carried out in two or more reactors configured in series or in parallel.