Search

CN-122006789-A - Method for synthesizing Ce-loaded ZSM-5 molecular sieve with assistance of graphene oxide

CN122006789ACN 122006789 ACN122006789 ACN 122006789ACN-122006789-A

Abstract

The invention discloses a method for synthesizing a Ce-loaded ZSM-5 molecular sieve with the assistance of graphene oxide, and relates to the technical field of molecular sieve preparation. According to the method, a cerium salt precursor is firstly introduced into a graphene oxide system to realize loading and stabilization of Ce element on the surface of graphene oxide, then the composite is added into a ZSM-5 molecular sieve precursor, and crystallization is induced under a microwave hydrothermal condition to obtain the mesoporous ZSM-5 molecular sieve material with a regular structure. In the obtained material, the graphene oxide effectively improves the crystal morphology and mesoporous structure of the molecular sieve, and promotes the dispersion and fixation of Ce element on the framework and the surface, thereby remarkably improving the catalytic performance and stability of the material. The method has the advantages of simple operation, short synthesis period and strong controllability, and the prepared Ce-loaded mesoporous ZSM-5 molecular sieve has wide application prospect in the fields of hydrocarbon conversion and the like.

Inventors

  • XU LEI
  • ZHANG YIXUAN
  • XIE CHENG
  • LU JUNYU
  • YAO GUANGSHENG
  • LIU YANZHI
  • YIN HAO
  • WANG JING

Assignees

  • 昆明理工大学

Dates

Publication Date
20260512
Application Date
20260121

Claims (8)

  1. 1. The method for synthesizing the Ce-loaded ZSM-5 molecular sieve with the assistance of graphene oxide is characterized by comprising the following steps of: S1, dispersing graphene oxide in deionized water to obtain a uniform dispersion liquid, adding a cerium salt precursor into the dispersion liquid, and stirring for 3-4 hours under stirring or ultrasonic conditions to enable Ce 3+ to be loaded on the surface of the graphene oxide, so as to obtain a Ce-GO compound; s2, mixing a silicon source, an aluminum source, a template agent and deionized water, and stirring for 1-2 hours to obtain a precursor a; s3, adding the Ce-GO compound obtained in the S1 into the precursor a of the S2, fully and uniformly stirring, then placing the mixture into a microwave hydrothermal reaction device, and reacting for 2-4 hours at 160-190 ℃ to induce the Ce-GO compound to form a product b; And S4, placing the product b in a muffle furnace for roasting to remove the template agent and the graphene oxide, and performing ion exchange to obtain the Ce-loaded ZSM-5 molecular sieve with the mesoporous structure.
  2. 2. The method of claim 1, wherein the graphene oxide is added in an amount of 20-100 mg/L in the step S1.
  3. 3. The method of claim 1, wherein in the step S1, the cerium salt precursor is cerium nitrate or cerium acetate, and the mass ratio of the cerium salt precursor to the graphene oxide is 0.5-10:1.
  4. 4. The method of claim 1, wherein in the step S2, the silicon source is one of liquid silica gel and tetraethyl orthosilicate, the template agent is one of tetrapropylammonium hydroxide and tetrapropylammonium bromide, and the molar ratio of the silicon source to the template agent is 3-4:1.
  5. 5. The method of claim 1, wherein in the step S3, the Ce-GO complex is added to the precursor a of S2, and then the mixture is ultrasonically stirred at room temperature for 4 to 6 hours.
  6. 6. The method of claim 1, wherein the microwave hydrothermal power in the step S3 is 1000-2000W.
  7. 7. The method according to claim 1, wherein in the step S4, the temperature is raised to 500-700 ℃ at a temperature rise rate of 5-20 ℃ per minute, and the temperature is kept for 5-7 hours.
  8. 8. The method of claim 1, wherein in the step S4, the ion exchange is performed by using 1 mol/L NH 4 NO 3 or NH 4 Cl solution as an ion exchanger, the mass ratio of the ion exchanger to the product b is 20:1, the ion exchange temperature is 60-70 ℃, and the ion exchange time is 5-7 hours.

Description

Method for synthesizing Ce-loaded ZSM-5 molecular sieve with assistance of graphene oxide Technical Field The invention relates to the technical field of molecular sieve preparation, in particular to a method for synthesizing a Ce-loaded ZSM-5 molecular sieve with the assistance of graphene oxide. Background With the massive use and disposal of plastic products, the environmental pressure of plastic waste is increasing. Pyrolysis technology is taken as an important way for recycling waste plastics, and can crack high molecular chains into low molecular weight hydrocarbon compounds, wherein olefin products have higher industrial application value. However, the conventional pyrolysis process has the problems of uneven product distribution, serious coking, poor selectivity and the like, and a high-efficiency stable catalyst needs to be developed to improve the pyrolysis reaction process. ZSM-5 molecular sieve is widely used for plastic pyrolysis catalysis due to its unique pore structure and acidic sites. However, the traditional microporous ZSM-5 has the defects of limited diffusion, accelerated coking, insufficient utilization rate of active centers and the like in the catalytic process. In addition, it is difficult for a single ZSM-5 to combine high activity with high selectivity of the product during the cracking process. In the embodiment 2 of CN115990509A specification, a preparation method of a ZSM-5 molecular sieve loaded with cerium element is disclosed, graphene oxide is firstly subjected to dipping, drying and roasting, then cerium nitrate solution is added, and metal elements are finally dipped and introduced, so that agglomeration of metal on the outer surface is easy to cause, and the preparation steps are complex and long in time consumption. Disclosure of Invention The invention aims to provide a method for synthesizing a Ce-loaded ZSM-5 molecular sieve with the assistance of graphene oxide, which solves the problems of complicated and long process time consumption and unsatisfactory effect of the existing method. The method combines microwave hydrothermal treatment to realize the rapid synthesis of the Ce-loaded ZSM-5 molecular sieve and the formation of a mesoporous structure. In order to achieve the above purpose, the present invention adopts the following technical scheme: the method for synthesizing the Ce-loaded ZSM-5 molecular sieve with the assistance of graphene oxide is characterized by comprising the following steps of: S1, dispersing graphene oxide in deionized water to obtain uniform dispersion liquid, adding a cerium salt precursor into the dispersion liquid to enable Ce 3+ to be loaded on the surface of the graphene oxide, and obtaining a Ce-GO compound; s2, mixing a silicon source, an aluminum source, a template agent and deionized water, and stirring for 1-2 hours to obtain a precursor a; s3, adding the Ce-GO compound obtained in the S1 into the precursor a of the S2, fully and uniformly stirring, then placing the mixture into a microwave hydrothermal reaction device, and reacting for 2-4 hours at 160-190 ℃ to induce the Ce-GO compound to form a product b; And S4, placing the product b in a muffle furnace for roasting to remove the template agent and the graphene oxide, and performing ion exchange to obtain the Ce-loaded ZSM-5 molecular sieve with the mesoporous structure. In a further technical scheme, in the step S1, the addition amount of the graphene oxide is 20-100 mg/100mL. In a further technical scheme, in the step S1, the cerium salt precursor is cerium nitrate or cerium acetate, and the mass ratio of the cerium salt precursor to the graphene oxide is 0.5-10:1. In a further technical scheme, in the step S2, the silicon source is one of liquid silica gel and tetraethyl orthosilicate, the template agent is one of tetrapropylammonium hydroxide and tetrapropylammonium bromide, the molar ratio of the silicon source to the template agent is 3-4:1, and the aluminum source is determined according to the silicon-aluminum ratio of the required ZSM-5 molecular sieve. In a further technical scheme, in the step S3, after the Ce-GO compound is added into the precursor a of the S2, the mixture is ultrasonically stirred for 4-6 hours at room temperature. In a further technical scheme, in the step S3, the microwave hydrothermal power is 1000-2000W. In a further technical scheme, in the step S4, the temperature is raised to 500-700 ℃ at a temperature rising rate of 5-20 ℃ per minute, and the temperature is kept for 5-7 hours. In a further technical scheme, in the step S4, 1 mol/L NH 4NO3 or NH 4 Cl solution is used as an ion exchanger in ion exchange, the mass ratio of the ion exchanger to the product b is 20:1, the ion exchange temperature is 60-70 ℃, and the ion exchange time is 5-7 hours. In a further technical scheme, in the step S4, the Ce-loaded ZSM-5 molecular sieve is a typical MFI framework, the aperture is in the range of 1-50 nm, the specific surface area is 400-600 m 2/g, and