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CN-121972201-A - Nitrogen-doped PVC dechlorinated carbon loaded iron catalyst, preparation method thereof and application thereof in polyolefin pyrolysis reaction

CN121972201ACN 121972201 ACN121972201 ACN 121972201ACN-121972201-A

Abstract

The invention discloses a nitrogen-doped PVC dechlorinated carbon loaded iron catalyst, a preparation method thereof and application thereof in polyolefin pyrolysis reaction. The nitrogen-doped PVC dechlorinated carbon loaded iron catalyst is obtained by taking iron oxide as an iron source, melamine as a nitrogen source and PVC as a carbon source through high-temperature calcination. The catalyst prepared by the invention can realize the pyrolysis of polyolefin under the inert atmosphere of 360 ℃, and the pyrolysis oil yield can reach 88% (. Gtoreq.C6). The catalyst prepared by the invention can be expanded to pyrolysis of commercial waste polyolefin plastics, and pyrolysis oil with 80-88% yield is obtained. Compared with the traditional pyrolysis catalyst, the catalyst has the advantages of high catalytic activity, easy preparation, low cost, good stability and easy recovery, and the activity of the catalyst can be recovered through simple high-temperature calcination after the activity of the catalyst is reduced.

Inventors

  • ZHANG JIAHAO
  • LU GUOPING
  • TAN CHENHAO
  • JIA KAI
  • Du Yinzhen
  • SHI NAN

Assignees

  • 内蒙古生力民爆股份有限公司
  • 南京理工大学

Dates

Publication Date
20260505
Application Date
20260127

Claims (7)

  1. 1. The preparation method of the nitrogen-doped PVC dechlorinated carbon loaded iron catalyst is characterized by comprising the following steps of: Placing melamine into a tube furnace, heating to 550 ℃ at a rate of 5 ℃ per minute, and calcining 4h under a nitrogen atmosphere to obtain C 3 N 4 ; Mixing PVC and ferric oxide, and performing pyrolysis dechlorination for 30min at 220 ℃, wherein the obtained solid is marked as Fe@C PVC ; And thirdly, ball-milling and mixing Fe@C PVC and the C 3 N 4 obtained in the first step according to a mass ratio of 1:1, heating to 700 ℃ at a speed of 5 ℃ per minute under a nitrogen atmosphere, preserving heat for 2h, and grinding to obtain the nitrogen-doped PVC dechlorinated carbon loaded iron catalyst.
  2. 2. The method for preparing the nitrogen-doped PVC dechlorinated carbon supported iron catalyst according to claim 1, wherein the mass ratio of the PVC to the ferric oxide in the second step is 20:1.
  3. 3. A nitrogen-doped PVC dechlorinated carbon supported iron catalyst prepared by the method of preparing a nitrogen-doped PVC dechlorinated carbon supported iron catalyst of claim 1.
  4. 4. Use of the nitrogen-doped PVC dechlorinated carbon supported iron catalyst of claim 3 in a polyolefin pyrolysis reaction.
  5. 5. The application of the nitrogen-doped PVC dechlorinated carbon supported iron catalyst in polyolefin pyrolysis reaction according to claim 4, wherein the method comprises the steps of placing polyolefin and the nitrogen-doped PVC dechlorinated carbon supported iron catalyst in a reactor, uniformly mixing, carrying out gas exchange by using N 2 , carrying out pyrolysis reaction at 320-400- o ℃ for 30-120 min, and separating the catalyst from pyrolysis products after the reaction is finished.
  6. 6. The application of the nitrogen-doped PVC dechlorinated carbon supported iron catalyst in polyolefin pyrolysis reaction according to claim 5, wherein the mass ratio of the polyolefin to the nitrogen-doped PVC dechlorinated carbon supported iron catalyst is 40:0.5-2.
  7. 7. The use of the nitrogen-doped PVC dechlorinated carbon supported iron catalyst according to claim 6, wherein the mass ratio of polyolefin to nitrogen-doped PVC dechlorinated carbon supported iron catalyst is 40:1.

Description

Nitrogen-doped PVC dechlorinated carbon loaded iron catalyst, preparation method thereof and application thereof in polyolefin pyrolysis reaction Technical Field The invention belongs to the technical field of plastic degradation, and particularly relates to a nitrogen-doped PVC dechlorinated carbon loaded iron catalyst, a preparation method thereof and application thereof in polyolefin pyrolysis reaction. Background Polyethylene (PE) is one of the most widely used general plastics, and is widely used in many fields such as packaging, agriculture, construction, and automobiles, and is a plastic variety with the greatest global yield due to its excellent chemical resistance, mechanical strength, and processability. However, of the 3.8 million tons of plastic produced annually worldwide, nearly 75% are discarded after a single use. The PE molecular chain has extremely strong chemical stability and hydrophobicity, so that the PE molecular chain is difficult to be degraded by microorganisms in natural environment, and a large amount of waste PE products are accumulated for a long time to form 'white pollution', so that serious harm is caused to soil, water, ecosystem and human health, and the PE molecular chain has become a serious environmental problem to be solved in the global urgent need. Pyrolysis technology has wide potential in industrial application due to simple operation and good adaptability to various raw materials. When pyrolysis is carried out in a high-temperature anaerobic environment at 400-900 ℃, polyolefin can be converted into low-molecular-weight hydrocarbon, and the products can be further refined into fuel or converted into other high-added-value materials. However, the current pyrolysis technology still faces three key challenges, namely, how to reduce the pyrolysis temperature to reduce energy consumption, how to reduce the catalyst usage and improve the catalytic efficiency, and how to regulate the carbon chain component of the product to optimize the product value. The catalyst plays an indispensable key role in the pyrolysis process, can greatly reduce the pyrolysis reaction temperature and improve the pyrolysis efficiency, and can regulate and control the component distribution of the product by virtue of reasonable design of the morphology, pore channel structure and pH value of the catalyst carrier. The acidic zeolite ZSM-5, beta and solid acid carrier material loaded with noble metal clusters are the conventional choice type of polyolefin pyrolysis catalyst, but the pyrolysis temperature is as high as 400 ℃, and the higher acidity can generate lighter hydrocarbons but also accelerate the generation of coke, thereby further inactivating the catalyst. In recent years, scientific researchers have made many efforts to solve the problem of high pyrolysis energy consumption. Modified layered zeolite, ZSM-5 nanosheets (Angew. Chem. Int. Ed. 2024, 63, e 202405252.), SO 4/ZrO2-Al2O3 materials (Angew. Chem. Int. Ed. 2024, 64, e 202417923.) can achieve pyrolysis of polyolefin in a lower temperature range (240-280 ℃). However, the method has the problems of large catalyst consumption and long reaction time, which not only increases the recovery cost, but also restricts the application feasibility of the method in large-scale industrial scenes. In addition, in the polyolefin pyrolysis process, the regulation of the chain length and distribution of pyrolysis products is also a key problem to be solved in a key way. Therefore, a more green and efficient method is developed to pyrolyze and convert polyolefin into high-value liquid products, and the method has urgent practical demands and important significance. Disclosure of Invention The invention aims to overcome the defects of the prior art and provides a nitrogen-doped PVC dechlorinated carbon loaded iron catalyst, a preparation method thereof and application thereof in polyolefin pyrolysis reaction. Compared with the traditional pyrolysis catalyst, the catalyst obtained by the invention has high catalytic activity, easy preparation, low cost, good stability and easy recovery. In order to achieve the above purpose, the technical scheme adopted by the invention is as follows: The preparation method of the nitrogen-doped PVC dechlorinated carbon loaded iron catalyst comprises the following steps: Placing melamine into a tube furnace, heating to 550 ℃ at a rate of 5 ℃ per minute, and calcining 4h under a nitrogen atmosphere to obtain C 3N4; mixing PVC and ferric oxide, and performing pyrolysis dechlorination for 30min at 220 ℃, wherein the obtained solid is marked as Fe@C PVC; And thirdly, ball-milling and mixing Fe@C PVC and the C 3N4 obtained in the first step according to a mass ratio of 1:1, heating to 700 ℃ at a speed of 5 ℃ per minute under a nitrogen atmosphere, preserving heat for 2h, and grinding to obtain the nitrogen-doped PVC dechlorinated carbon loaded iron catalyst. Further, the preparation method of the nitrogen-doped PVC dechlor