Debromination of pyrolysis oil from brominated epoxy resin by two-stage pyrolysis: roles and potential of attapulgite

Pyrolysis is a key technology for the efficient and safe debromination of brominated epoxy resins (BERs) in waste printed circuit boards (WPCBs). However, conventional pyrolysis often suffers from insufficient debromination of the pyrolysis oil, which restricts its subsequent utilization. Herein, a two-stage integrated pyrolysis process coupling thermal debromination with catalytic pyrolysis is proposed for enhanced bromine removal and quality upgrading of pyrolysis oil. The results show that increasing the temperature in the downstream reaction zone promotes secondary cracking of volatiles, significantly reducing the bromine content while simultaneously increasing the relative content of high-value aromatics. When the temperature of second-stage reaction zone reached 700 °C, the bromine content in the pyrolysis oil decreased to 24.87%, whereas the aromatic hydrocarbon content increased to 45.31%. The introduction of attapulgite (ATP) further promoted bromine removal. Notably, alkali modification exposed the metal active sites of ATP and introduced sodium species, thereby facilitating C–Br bond cleavage and increasing the debromination efficiency to 72.94%. This method offers valuable guidance for the valorization of bromine-containing solid waste and novel insights into environmentally sound disposal of WPCBs.