Enhanced microwave absorption capacity of iron-based catalysts by introducing Co and Ni for microwave pyrolysis of waste COVID-19 Masks. (15th May 2023)

• Record Type: Journal Article
• Authors: Yuwen, Chao; Liu, Bingguo; Rong, Qian; Hou, Keren; Zhang, Libo; Guo, Shenghui
• Is Part Of: Fuel. Volume 340(2023)
• Publication Date: 2023-05-15
• Subjects: Discarded COVID-19 masks -- Microwave-assisted pyrolysis -- Iron-based catalyst -- Dielectric properties; Fuel -- Periodicals; Coal -- Periodicals; Coal; Fuel; Periodicals; 662.6
• DOI: 10.1016/j.fuel.2023.127551
• Languages: English
• ISSNs: 0016-2361

Abstract

Graphical abstract: Highlights: Lattice defects induced by Co and Ni adding enhances microwave absorbtion of FeAl. Masks were microwave pyrolyzed by FeCoAl to 77 wt% gas and 20 wt% CNTs within 14 min. Content of CO and H2 in the gas of masks microwave pyrolyzed by FeCoAl is over 90 vol%. Dehydrogenation efficiency of FeCoAl catalyst is 38.66 mmolH2 ·g −1 Masks . Abstract: Inexpensive iron-based catalysts are the most promising catalysts for microwave-assisted deconstruction of waste plastics. However, the microwave heating efficiency of most of the synthesized iron-based catalysts is very low, in particular, the FeAl catalyst was prepared by microwave combustion method, and its mixture with disposable medical masks (DMMs) was only heated to about 150℃ within 10 min. Here, we introduce the second-phase metals (Co or Ni) into the FeAl catalyst, resulting in the rearrangement of the catalyst structure and electrons to give the catalyst good microwave absorption ability. The mixture of the catalyst and DMMs can be quickly heated to above 900℃ in 10 min, especially after reaching the melting point of plastic, the instantaneous heating rate reaches 350 ℃·min −1 . under the unique microwave hot-spot pyrolysis mechanism, DMMs can be rapidly pyrolyzed into carbon nanotubes (19.65 wt%) and gas (77.65 wt%) within 14 min due to the efficient dehydrogenation efficiency and activity of Co. The corresponding H2 yield is up to 38.66 mmolH2 ·g −1 DMMs, and the percentage of CO and H2 in the gas is as high as 90 wt%. This work improves the microwave conversion efficiency of iron-based catalysts by introducing second phase metals, and waste DMMs were efficiently converted into CO, H2 and CNTs, which can also be extended to other polymer or biomass chemical cycles.