Pyrolysis-catalysis of different waste plastics over Fe/Al2O3 catalyst: High-value hydrogen, liquid fuels, carbon nanotubes and possible reaction mechanisms

• Published in: Energy conversion and management Vol. 229; p. 113794
• Main Authors: Cai, Ning, Li, Xiaoqiang, Xia, Sunwen, Sun, Lin, Hu, Junhao, Bartocci, Pietro, Fantozzi, Francesco, Williams, Paul T., Yang, Haiping, Chen, Hanping
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.02.2021; Elsevier Science Ltd
• Subjects: Aluminum oxide; Carbon; Carbon nanotubes; Catalysis; Catalysts; Correlation; High density polyethylenes; High-value products; Liquid fuels; Low density polyethylenes; Nanotechnology; Nanotubes; Plastic debris; Polyethylene; Polyolefins; Polypropylene; Polystyrene; Polystyrene resins; Pyrolysis; Pyrolysis-catalysis; Reaction mechanisms; Waste plastics; Yield; Waste plastics; Correlation; Pyrolysis-catalysis; Reaction mechanisms; High-value products
• ISSN: 0196-8904; 1879-2227
• DOI: 10.1016/j.enconman.2020.113794

[Display omitted] •The pyrolysis-catalysis of various types plastics was studied at 800 °C.•Different plastics has notably influence on the products distribution and properties.•PP and PE produced less carbon deposition with higher purity of CNTs (~80%).•PS derived lower yield of gaseous but higher proportion of hydrogen (75 vol%).•PS produced around 50 wt% carbon deposits with much amorphous carbon. To understand the correlation between plastic structure and products, and the possible reaction mechanisms, the pyrolysis–catalysis of different types of waste plastics was investigated in the presence of an Fe/Al2O3 catalyst. Polypropylene (PP), high-density polyethylene (HDPE), low-density polyethylene (LDPE), high-impact polystyrene (HIPS), and general-purpose polystyrene (GPPS) were used as the feedstock. The results showed that PP, HDPE, and LDPE showed higher H2-enriched gaseous product yields (>40 wt%), but higher H2 concentration (over 70 vol%) was obtained from the gaseous products of HIPS and GPPS. In terms of liquid oil, the yield exhibited a relatively stable tendency, which was ~ 20 wt%, and the liquid product comprised hydrocarbons with a carbon number range mainly between 8 and 16. For solid carbon deposits, HIPS waste plastic led to a higher solid deposit yield of 49.4 wt%, followed by GPPS of 48.7 wt%. By contrast, PP, HDPE, and LDPE showed lower yields of 30.2 wt%, 36.9 wt%, and 35.9 wt%, respectively. In summary, more, purer and cleaner carbon nanotubes (CNTs) could be obtained from pyrolysis–catalysis of polyolefin (PP and PE), while more amorphous carbon and hydrogen were gathered from PS.