Full Recovery of Epoxy Resin Wastes into Bisphenol A and Epoxy Monomers via Lewis Acid

Epoxy resins (EPs) are important thermosetting plastics and difficult to recycle because of their stable cross-linked structure. In this study, we report a full recovery strategy for the conversion of EPs into high-value platform compounds, i.e., bisphenol A (BPA) and epoxy monomers such as 4,4'-methylenebis (N,N'-diglycidylaniline) (AG80), which involves the selective breaking of the C(sp³)─O bond using commercially available boron trichloride (BCl₃), the reconstruction of the broken C(sp³)─N bond and the cyclization of the hydroxy groups. The yield of BPA is 93 wt% with a purity of 99%, and the yield of AG80 is 96 wt% with an epoxy value of 0.43. 100% recovery of EP elements was achieved theoretically, and the actual mass recovery of the EPs is as high as 91%. Because of its versatility, simplicity of operation, mild reaction conditions, and recyclability of all solvents and by-products, this approach shows the potential in solving the current recycling challenges associated with EP waste.