Conversion of microwave pyrolysed ASR's char using high temperature agents.

Area of Science:

• Waste Management & Valorization
• Chemical Engineering
• Materials Science

Background:

• Automotive shredder residue (ASR) is a complex waste stream containing valuable metals and organic feedstock.
• Pyrolysis of ASR generates solid products that are morphologically and chemically diverse, including hazardous heavy metals.
• Understanding the conversion of organic residues from ASR pyrolysis is crucial for effective waste valorization.

Purpose of the Study:

• To investigate the gasification of organic residues from microwave-pyrolyzed ASR.
• To determine the effect of temperature and gasifying agents (steam vs. oxygen) on char conversion rates.
• To elucidate the fundamental mechanisms governing char decomposition during ASR pyrolysis.

Main Methods:

• Laboratory-scale plug-flow gasifier experiments.
• Thermogravimetric analysis (macro TG) at 950, 850, and 760 °C to monitor mass loss.
• Investigation of carbon conversion rates during gasification and pyrolysis stages.

Main Results:

• Char conversion rate decreased as external gas temperature increased, irrespective of the gasifying agent.
• No significant difference in char decomposition reaction rates was observed between steam and oxygen treatments.
• The observed char behavior may be attributed to ash inhibition (e.g., alkali metals) or structural deformation from microwave heating.

Conclusions:

• Temperature is a key factor influencing char conversion in ASR pyrolysis, with higher temperatures leading to lower conversion rates.
• The choice between steam and oxygen as gasifying agents showed minimal impact on char decomposition kinetics under the tested conditions.
• Further research is needed to fully understand the inhibiting effects of ash components and microwave-induced structural changes on char reactivity.