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CN-121990590-A - ZSM-5 nanosheet catalyst and preparation method and application thereof

CN121990590ACN 121990590 ACN121990590 ACN 121990590ACN-121990590-A

Abstract

The invention relates to a ZSM-5 nanosheet catalyst and a preparation method and application thereof, belonging to the technical field of catalysts, wherein the preparation method regulates and controls the morphology of the catalyst through specific silicon-aluminum ratio and fluorine-aluminum ratio, therefore, the obtained ZSM-5 nanosheet catalyst has excellent catalytic effect, and can effectively degrade and recycle the waste cable crosslinked polyethylene into a series of gaseous and liquid hydrocarbons, so that the high-value utilization of the waste cable crosslinked polyethylene is realized.

Inventors

  • PENG XIANGYANG
  • PAN HONGFEI
  • WANG ZHENG
  • ZHANG HAINING
  • FAN YAZHOU
  • LIU LIN
  • ZHAO BING
  • HUANG SIHAO
  • ZHU PEIQING
  • YU SHIHU

Assignees

  • 广东电网有限责任公司电力科学研究院
  • 广东电网有限责任公司汕尾供电局

Dates

Publication Date
20260508
Application Date
20260402

Claims (10)

  1. 1. The preparation method of the ZSM-5 nanosheet catalyst is characterized by comprising the following steps of: step (1), removing ethanol after stirring tetraethyl silicate and tetrapropylammonium hydroxide for reaction, and crystallizing to obtain a precursor solution; step (2) adding tetraethyl silicate and tetrapropylammonium hydroxide into the precursor solution obtained in the step (1) and mixing to obtain a solution A, mixing an aluminum salt solution and an ammonium fluoride solution to obtain a solution B, wherein the molar ratio of fluorine ions to aluminum ions in the solution B is (5-20): 1, and the ratio of the total molar amount of the tetraethyl silicate in the step (1) and the tetraethyl silicate in the step (2) to the molar amount of aluminum ions in the solution B is (15-40): 1; and (3) mixing the solution A obtained in the step (2) with the solution B for hydrothermal reaction, centrifuging, washing, drying, and calcining to obtain the ZSM-5 nanosheet catalyst.
  2. 2. The method for producing a ZSM-5 nanosheet catalyst according to claim 1, wherein the ratio of the total molar amount of tetraethyl silicate in step (1) and tetraethyl silicate in step (2) to the molar amount of aluminum ions in the solution B is (18-37): 1, and/or the mass ratio of tetraethyl silicate to tetrapropylammonium hydroxide in step (1) is (2-3): 3-4).
  3. 3. The method for producing a ZSM-5 nanosheet catalyst according to claim 1, wherein in the step (1), the temperature of the stirring reaction is 30 to 50 ℃ for 4.5 to 10 hours, and/or the temperature of the crystallization is 60 to 80 ℃ for 36 to 60 hours, and/or the ratio of the total molar amount of tetraethyl silicate in the step (1) and tetraethyl silicate in the step (2) to the molar amount of aluminum ions in the solution B is (35 to 37): 1.
  4. 4. The method for preparing a ZSM-5 nanosheet catalyst according to claim 1, wherein in the step (2), the mass ratio of the precursor solution, tetraethyl silicate and tetrapropylammonium hydroxide is (25-30): 8-12): 5-6.5, and/or the molar ratio of fluoride ions to aluminum ions in the solution B is (7-16): 1.
  5. 5. The method according to claim 1, wherein in the step (2), the mixing temperature is 30 ℃ to 40 ℃ and the mixing time is 3h to 6h, and/or in the step (2), the mass ratio of the ammonium fluoride to tetrapropylammonium hydroxide is (1.2 to 1.6): 5 to 6.5, and/or the aluminum salt comprises at least one of aluminum sulfate, aluminum nitrate and aluminum chloride, and/or the molar ratio of fluoride ions to aluminum ions in the solution B is (14 to 16): 1.
  6. 6. The method for preparing ZSM-5 nanosheet catalyst as claimed in claim 1, wherein in the step (3), the hydrothermal reaction is performed at a temperature of 160-180 ℃ for a time of 10 h-16 h.
  7. 7. The method for producing a ZSM-5 nanosheet catalyst according to claim 1, wherein in the step (3), the drying temperature is 70℃to 100℃for a time of 10 h to 14 h, and/or the calcination temperature is 500℃to 600℃for a time of 4 h to 8 h, and/or the temperature rising rate at the time of calcination is 2℃to 10℃per minute.
  8. 8. The ZSM-5 nanosheet catalyst prepared by the process of any of claims 1-7.
  9. 9. Use of the ZSM-5 nanosheet catalyst of claim 8 for catalytic recovery of crosslinked polyethylene.
  10. 10. The use of the ZSM-5 nano-sheet catalyst according to claim 9 for recycling the catalytic crosslinked polyethylene, wherein the method for recycling the catalytic crosslinked polyethylene by the ZSM-5 nano-sheet catalyst is characterized in that the ZSM-5 nano-sheet catalyst is mixed with the crosslinked polyethylene and pyrolyzed in an inert atmosphere to obtain a liquid product and a gaseous product.

Description

ZSM-5 nanosheet catalyst and preparation method and application thereof Technical Field The invention belongs to the technical field of catalysts, and particularly relates to a ZSM-5 nanosheet catalyst and a preparation method and application thereof. Background Crosslinked polyethylene (XLPE) is widely used for external insulation of power transmission lines due to its excellent electrical properties and thermal stability, often as a core insulation medium for high voltage cables. The XLPE insulating layer is an insulating layer with a specified thickness which is formed by fully and uniformly mixing Polyethylene (PE) resin base materials, cross-linking agents, stabilizing agents and other auxiliary agents in a high-speed mixer, heating, melting and plasticizing in an extruder and uniformly extruding and wrapping on a conductor or an inner shielding layer. With the continuous expansion of the use scale of the high-voltage cable and the gradual expiration of the service period, the production of the retired cable increases year by year. Because the operation environment of the cable is complex, the insulating layer of the cable can be gradually aged and damaged under the comprehensive action of external factors such as photo-thermal water oxygen and the like, so that the insulating performance of the cable is reduced, and the searching of the recycling circulation path of the retired XLPE cable is particularly important. At present, the metal conductors in the cable form mature recycling paths, but a certain technical bottleneck still exists in the recovery of XLPE. The recovery method of the XLPE outer insulating layer mainly comprises the methods of mechanical recovery, chemical recovery, energy recovery and the like. The mechanical recovery mainly adopts a physical method to crush the cable and convert the cable into a series of functional fillers. Compared with the traditional PE material, the three-dimensional network structure formed by cross-linking XLPE molecular chains causes poor fluidity, and is difficult to finish reprocessing under the traditional extrusion process. Chemical recovery mainly comprises methods such as pyrolysis, hydrocracking and the like. The methods can decompose XLPE into small molecular compounds or monomers to different degrees and further convert the small molecular compounds or monomers into products with higher added values. Pyrolysis refers to a process in which XLPE is decomposed by heating to about 500 ℃ under anaerobic conditions. The C-C bond of the macromolecular chain can be broken randomly in the pyrolysis process, the carbon number of the product is widely distributed and is difficult to control the composition of the product, and the improvement of the pyrolysis temperature is beneficial to the improvement of the yield of the low-carbon number product, but the energy consumption is higher. The hydrocracking process converts the polymer into high quality fuel by C-C bond cleavage and hydrogenation reactions. The hydrocracking product has high saturation, less equipment corrosion, but high catalyst consumption, and the solvent/catalyst auxiliary method is easy to produce secondary pollution, thereby increasing the post-treatment difficulty. The existing recovery process generally has the problems of poor product controllability, higher energy consumption and cost, lower added value of the product and the like, and is difficult to realize large-scale and efficient green recycling. In summary, various technologies face the problem of balancing economy and environmental protection. Therefore, development of a recycling method for XLPE which can mildly and efficiently modify XLPE, can realize controllable product composition, low energy consumption and high added value at the same time is needed to break through the technical bottleneck of large-scale green recovery of retired XLPE cable insulating materials. Disclosure of Invention The invention aims to overcome the problems in the prior art and provides a ZSM-5 nanosheet catalyst as well as a preparation method and application thereof. The catalyst provided by the invention can effectively degrade and recycle the waste cable crosslinked polyethylene into a series of gaseous and liquid hydrocarbons, thereby realizing high-value utilization. The invention is realized by the following technical scheme: In a first aspect, the invention provides a method for preparing a ZSM-5 nanosheet catalyst, comprising the steps of: step (1), removing ethanol after stirring tetraethyl silicate (TEOS) and tetrapropylammonium hydroxide (TPAOH) for reaction, and crystallizing to obtain a precursor solution; step (2) adding tetraethyl silicate and tetrapropylammonium hydroxide into the precursor solution obtained in the step (1) and mixing to obtain a solution A, mixing an aluminum salt solution and an ammonium fluoride solution to obtain a solution B, wherein the molar ratio of fluorine ions to aluminum ions in the solution B is (5-20):