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CN-118663307-B - Toluene shape-selective disproportionation catalyst and preparation method and application thereof

CN118663307BCN 118663307 BCN118663307 BCN 118663307BCN-118663307-B

Abstract

The invention discloses a toluene shape-selective disproportionation catalyst and a preparation method and application thereof. The toluene shape-selective disproportionation catalyst comprises a modified ZSM-5 molecular sieve loaded with alkaline earth metal and macroporous alumina, wherein the total acid amount is 0.15-0.25 mmol/g, the acid amount outside a micropore duct is not higher than 5.0 mu mol/g, preferably 0.5-3.0 mu mol/g, the pore volume is 0.18-0.30 cm 3 /g, the micropore volume is 0.05-0.12 cm 3 /g, and the mass content of the modified ZSM-5 molecular sieve is 40-95% and the mass content of the alkaline earth metal is 0.5-1.5% based on the weight of the toluene shape-selective disproportionation catalyst. The preparation method of the catalyst comprises the preparation process of the alkaline earth metal-loaded modified ZSM-5 molecular sieve and the preparation process of the alkaline earth metal-loaded modified ZSM-5 molecular sieve-containing catalyst. The catalyst has simple preparation process, the acidity of the outer surface of the catalyst is reduced, the smoothness of a catalyst pore canal is not influenced, the selectivity of dimethylbenzene is improved, the side reactions such as aromatic hydrocarbon condensation and the like can be obviously reduced, carbon deposition is reduced, and the service life of the catalyst is prolonged.

Inventors

  • HAO WENYUE
  • LIU CHANG
  • GUO JUNHUI
  • WANG FENGLAI
  • PENG SHAOZHONG
  • CAO JUNFENG

Assignees

  • 中国石油化工股份有限公司
  • 中石化（大连）石油化工研究院有限公司

Dates

Publication Date
20260505
Application Date
20230314

Claims (20)

  1. 1. A toluene shape-selective disproportionation catalyst is characterized by comprising a modified ZSM-5 molecular sieve loaded with alkaline earth metal and macroporous alumina, wherein the total acid amount is 0.15-0.25 mmol/g, the acid amount outside a micropore duct is not higher than 5.0 mu mol/g, the pore volume is 0.18-0.30 cm 3 /g, the micropore volume is 0.05-0.12 cm 3 /g, the mass content of the modified ZSM-5 molecular sieve is 40-95% and the mass content of the alkaline earth metal is 0.5-1.5% based on the weight of the toluene shape-selective disproportionation catalyst, and the preparation method of the catalyst comprises the preparation process of the modified ZSM-5 molecular sieve loaded with alkaline earth metal and the preparation process of the modified ZSM-5 molecular sieve catalyst loaded with alkaline earth metal, wherein the preparation method of the modified ZSM-5 molecular sieve loaded with alkaline earth metal comprises the following steps of (1) carrying out hydrothermal treatment on the hydrogen ZSM-5 molecular sieve; (2) Impregnating the material obtained in the step (1) with a pore canal protecting liquid, wherein the pore canal protecting liquid is one or more of isopropylamine solution, tetraethylammonium hydroxide solution and tetrapropylammonium hydroxide solution; (3) Treating the material obtained in the step (2) by adopting high-steric hindrance organic acid; (4) Mixing the material obtained in the step (3) with a dealumination silicon-supplementing reagent to dealuminate and supplement silicon; (5) And (3) performing alkaline earth metal modification on the material obtained in the step (4).
  2. 2. The catalyst of claim 1, wherein the toluene disproportionation catalyst has an acid content of 0.5 to 3.0 μmol/g outside the microporous channels.
  3. 3. The catalyst according to claim 1, wherein the total acid amount of the toluene shape-selective disproportionation catalyst is 0.17-0.22 mmol/g, and the acid amount outside the micropore path is 0.3-2.0. Mu. Mol/g.
  4. 4. The catalyst of claim 1, wherein the toluene disproportionation catalyst has a pore volume of 0.20 to 0.25cm 3 /g and a micropore volume of 0.06 to 0.09cm 3 /g.
  5. 5. The catalyst according to claim 1, wherein the mass content of alkaline earth metal of the toluene shape-selective disproportionation catalyst is 0.8-1.2% based on the weight of the toluene shape-selective disproportionation catalyst.
  6. 6. The catalyst according to claim 1, wherein the mass content of the modified ZSM-5 molecular sieve in the toluene shape selective disproportionation catalyst is 60-90% and the mass content of macroporous alumina is 5-37% based on the weight of the toluene shape selective disproportionation catalyst.
  7. 7. A method for preparing a toluene shape selective disproportionation catalyst according to any one of claims 1 to 6, characterized by comprising the preparation of an alkaline earth metal-loaded modified ZSM-5 molecular sieve and the preparation of an alkaline earth metal-loaded modified ZSM-5 molecular sieve-containing catalyst, wherein the preparation method of the alkaline earth metal-loaded modified ZSM-5 molecular sieve comprises the following steps: (1) Carrying out hydrothermal treatment on the hydrogen-type ZSM-5 molecular sieve; (2) Impregnating the material obtained in the step (1) with a pore path protecting liquid, wherein the concentration of the pore path protecting liquid is 0.8-2.0 mol/L; (3) The material obtained in the step (2) is treated by adopting high-steric hindrance organic acid, and the specific operation is that the material obtained in the step (2) is firstly mixed with water, and then the high-steric hindrance organic acid is added until the pH value of the solution is reduced to 7.0-5.0; (4) Mixing the material obtained in the step (3) with a dealumination silicon-supplementing reagent to dealuminate silicon-supplementing, wherein the dropping speed of the dealumination silicon-supplementing reagent is not more than 0.5 mL/min.g of the material obtained in the step (3); (5) And (3) performing alkaline earth metal modification on the material obtained in the step (4).
  8. 8. The method according to claim 7, wherein in the step (1), the hydrogen-type ZSM-5 molecular sieve has a SiO 2 /Al 2 O 3 molar ratio of 15-30, a specific surface area of 300-450 m 2 /g and a pore volume of 0.15-0.20 cm 3 /g.
  9. 9. The method of claim 7, wherein in the step (1), the specific treatment process in the hydrothermal treatment process is that a commercial hydrogen ZSM-5 molecular sieve is placed in a hydrothermal furnace, steam is introduced, and the treatment is carried out for 1h to 3h under the conditions that the temperature is 250 ℃ to 400 ℃ and the pressure is 0.05 to 0.2 MPa.
  10. 10. The method of claim 7, wherein in the step (2), the concentration of the pore canal protecting liquid is 1.1-1.5 mol/L.
  11. 11. The method of claim 7, wherein the highly sterically hindered organic acid is 2, 4-dimethylbenzenesulfonic acid and/or 2, 5-dimethylbenzoic acid.
  12. 12. The method of claim 7, wherein in step (3), The liquid-solid volume ratio of water to the material obtained in the step (2) is 2:1-6:1, and/or And adding the high-steric hindrance organic acid until the pH value of the solution is reduced to 5.5-6.5.
  13. 13. The method of claim 7, wherein in the step (4), the dealumination and silicon supplementing agent is at least one of an ammonium hexafluorosilicate solution and an ethyl orthosilicate solution, the molar concentration of the dealumination and silicon supplementing agent is 0.3-1.0 mol/L, the mass ratio of the material obtained in the step (3) to the dealumination and silicon supplementing solution is 1:1-1:5, and the mixing temperature is 60-100 ℃.
  14. 14. The method of claim 7, wherein the specific operation process of the step (4) is that the material obtained in the step (3) is heated to 60-100 ℃ rapidly, stirring is continued, dealumination and silicon supplementing reagent is dripped, stirring is continued for 60-120 min after dripping is finished, and the dripping speed is 0.2-0.4 mL/min.g of the material obtained in the step (3).
  15. 15. The method of claim 7, wherein in the step (4), the obtained material is washed, filtered, dried and roasted after dealumination and silicon supplementation, the drying temperature is 100-150 ℃, the drying time is 2-4 hours, the roasting temperature is 400-600 ℃, and the roasting time is 3-5 hours.
  16. 16. The method according to claim 7, wherein the alkaline earth metal in step (5) is at least one of beryllium, magnesium, calcium, strontium, and barium.
  17. 17. The method of claim 16, wherein the alkaline earth metal in step (5) is magnesium or calcium.
  18. 18. The method of claim 7, wherein the alkaline earth metal modification in the step (5) is that the material obtained in the step (4) is impregnated with an alkaline earth metal solution, and the mass concentration of the alkaline earth metal in the alkaline earth metal solution is 3.0-10.0%.
  19. 19. The method of claim 18, wherein the alkaline earth metal solution has a concentration of 5.0 to 8.0% by mass of alkaline earth metal.
  20. 20. The method of claim 7, wherein the preparation process of the modified ZSM-5 molecular sieve catalyst containing supported alkaline earth metal comprises kneading the modified ZSM-5 molecular sieve containing supported alkaline earth metal with macroporous alumina and a binder, extruding, molding, drying and roasting to obtain the toluene shape-selective disproportionation catalyst.

Description

Toluene shape-selective disproportionation catalyst and preparation method and application thereof Technical Field The invention belongs to the field of toluene disproportionation, relates to a toluene shape-selective disproportionation catalyst and a preparation method and application thereof, and in particular relates to a toluene shape-selective disproportionation catalyst with high activity and stability and a preparation method and application thereof. Background The traditional toluene disproportionation and alkyl transfer process is controlled by thermodynamic equilibrium, typical compositions of para-xylene isomer, meta-xylene isomer and ortho-xylene isomer are PX:MX:OX=24:54:22 (mol), the meta-xylene content is higher, the PX content is lower, the PX is increased by adsorption separation and C8 aromatic hydrocarbon isomerization processes, the production process flow is long, the material circulation amount is large, and the material consumption and energy consumption are higher. The toluene shape-selective disproportionation technology has high para-selectivity of the product, and can generate high-content paraxylene, thereby effectively reducing the separation cost of paraxylene. CN105013522B provides a toluene shape-selective disproportionation catalyst, its preparation method and use, and chemical liquid phase deposition modification of the acid modified catalyst parent, which can mask the acidity of the external surface while improving the accessibility of the active center of the molecular sieve. CN200910025152.6 discloses a preparation method of a Silicalite-1 molecular sieve membrane catalyst for toluene shape-selective disproportionation, which comprises the steps of adding ZSM-5 shaped carrier molecular sieve into crystallization liquid composed of a silicon source, a template agent, deionized water and absolute ethyl alcohol for twice in-situ hydrothermal crystallization, and finally, carrying out multiple exchange by using ammonium salt solution, drying and roasting to obtain the Silicalite-1 molecular sieve membrane catalyst. CN200610029951.7 discloses a catalyst for toluene shape selective disproportionation reaction to produce para-xylene. The ZSM-5 molecular sieve is adopted as a main active main body, the titanium silicate oxide is adopted as an inert binder, and the surface of the catalyst is modified by a silicon dioxide inert coating, so that the total pore volume of the catalyst is 0.27-0.45 ml/g, and the pore volume of a middle pore part with the pore diameter of more than or equal to 2nm accounts for 55-75% of the total pore volume. The mesoporous part with the aperture of more than or equal to 2nm is mainly provided by a binder, the content of the binder and the silicon dioxide coating is higher, and the realization operation of the silicon dioxide coating is complex. In the prior art, the selectivity of the catalyst is improved by modulating the ZSM-5 acidic structure through chemical deposition, generation of a pure silicon molecular sieve membrane, a silicon dioxide coating and the like, but the problems of blocking pore channels, needing a large amount of organic solvents, being complex in operation and the like in the acid modification process exist. Disclosure of Invention Aiming at the defects of the prior art, the invention provides a toluene shape-selective disproportionation catalyst, and a preparation method and application thereof. The catalyst has simple preparation process, the acidity of the outer surface of the catalyst is reduced, the smoothness of a catalyst pore canal is not influenced, the selectivity of dimethylbenzene is improved, the side reactions such as aromatic hydrocarbon condensation and the like can be obviously reduced, carbon deposition is reduced, and the service life of the catalyst is prolonged. The toluene shape-selective disproportionation catalyst comprises a modified ZSM-5 molecular sieve loaded with alkaline earth metal and macroporous alumina, wherein the total acid amount is 0.15-0.25 mmol/g, the acid amount outside a micropore duct is not higher than 5.0 mu mol/g, preferably 0.5-3.0 mu mol/g, the pore volume is 0.18-0.30 cm 3/g, the micropore volume is 0.05-0.12 cm 3/g, and the mass content of the modified ZSM-5 molecular sieve is 40-95% and the mass content of the alkaline earth metal is 0.5-1.5% based on the weight of the toluene shape-selective disproportionation catalyst. Further, preferably, the total acid amount of the toluene shape-selective disproportionation catalyst is 0.17-0.22 mmol/g, and the acid amount outside the micropore duct is not higher than 3.0 mu mol/g, preferably 0.3-2.0 mu mol/g. Further, preferably, the toluene shape-selective disproportionation catalyst has a pore volume of 0.20-0.25 cm 3/g, wherein the micropore volume is 0.06-0.09 cm 3/g. Further, preferably, the alkaline earth metal content of the toluene shape-selective disproportionation catalyst is 0.8-1.2% based on the weight of the toluene shape-sel