Pyrolysis Behavior of Waste Printed Circuit Boards in a Vertical Fixed Bed

Abstract

Rapid advancements in technology have triggered a substantial decrease in the lifespan of electronic goods, leading to a surge in waste printed circuit boards (WPCBs). Given the recyclable potential of WPCBs’ nonmetallic elements, it is imperative to devise an eco-friendly and cost-effective method for their treatment and recycling. This study delved into optimizing the pyrolysis process of WPCBs in a vertical fixed-bed reactor, examining both catalytic and noncatalytic scenarios. Our findings highlight that catalytic pyrolysis enhances both efficiency and product quality. Optimal conditions emerged with temperatures spanning 500–700 °C, heating rates of 10–20 °C/min, and a 30 min thermostatic time. To further elucidate the composition and structure of the pyrolysis products, Fourier transform infrared spectrometry (FTIR) and gas chromatography–mass spectrometry (GC–MS) analyses were employed. These analyses revealed that catalytic use reduces the yield of liquid and solid byproducts compared to noncatalytic processing. Specifically, the catalyst ZSM-5 facilitated secondary pyrolysis of liquid products, yielding prominent compounds such as 4-isopropyl phenol, p-phenylphenol, 4,4′-isopropylidenediphenol, p-isopropenyl phenol, and 1,2-dimethyl-4-azaphenanthrene-3-carboxylic acid.