The production of debrominated aromatics via the catalytic pyrolysis of flexible printed circuit boards
Sumin Pyo, Avnish Kumar, Moonis Ali Khan, Byong‐Hun Jeon, Siyoung Q. Choi, Young‐Min Kim, Young‐Kwon Park
Abstract
Pyrolysis is an environmental technology for the proper treatment of electronic waste (e-waste) for the production of fuel. However, the presence of brominated compounds in pyrolysis oil makes its commercialization difficult. In this study, various types of zeolites, HY (30), HZSM-5 (30), HZSM-5 (50), HZSM-5 (280), and basic metal oxides (MgO and CaO) were used for the pyrolysis of flexible printed circuit boards (FPCBs) for the first time to produce bromine-free oil. A higher production efficiency of debrominated aromatic hydrocarbons, primarily benzene, toluene, ethylbenzene, xylenes (BTEXs), and naphthalene with zeolites, was achieved over basic metal oxides. The use of HZSM-5 (HZ) (30) increased the amount of benzene (an area of 31.5 × 10 7 ) and toluene (an area of 17.6 × 10 7 ), and a high debromination efficiency was observed for basic metal oxides owing to the strong affinity of halides toward the Ca 2+ and Mg 2+ ions. Among the BTEXs, benzene (an area of 31.5 × 10 7 ) and toluene (an area of 17.6 × 10 7 ) were obtained as highly selective monoaromatics in the presence of the catalyst HZ (30). CaO and HZ (30) were effective for debromination and aromatic production, respectively. The in-situ CaO/ex-situ HZ (30) combination revealed ∼ 100% debromination efficiency; however, the total aromatic hydrocarbon production was higher on the in-situ HZ (30)/ex-situ CaO with ∼ 77.5% debromination efficiency. Meanwhile, the in-situ HZ (30)/ex-situ CaO configuration could achieve ∼ 100% debromination efficiency by increasing the amount of CaO to 7 times to feed.