Catalytic pyrolysis of waste printed circuit boards to organic bromine: reaction mechanism and comprehensive recovery.

Abstract

The production of waste printed circuit boards (WPCBs) is increasing, and its complex composition makes recycling difficult. In addition, the presence of heavy metals and brominated flame retardants makes it a hazardous waste. Therefore, its recycling is a necessary way for resource recycling and green sustainable development. The purpose of this study is to propose a green, efficient, and pollution-free recycling process as an alternative to recycle WPCBs. In this work, an alkaline metal oxide catalytic pyrolysis process was used to recover WPCBs. In the presence of alkali metal oxides (such as Ca(OH)2) and coexisting copper, Ca(OH)2 and coexisting copper are transformed into CaBr2 and Cu Br by reacting with organic bromine in WPCBs and remaining in the solid phase product. The bromine content and the proportion of inorganic bromine in the solid phase products were 87.68% and 87.56%, respectively. In addition, the content of organic bromine in the pyrolysis oil obtained by co-pyrolysis was significantly reduced. This study demonstrated the feasibility of Ca(OH)2 catalytic pyrolysis for WPCB recovery.