Boosting the VOCs purification over high-performance α-MnO2 separated from spent lithium-ion battery: Synergistic effect of metal doping and acid treatment

Abstract

Spent lithium-ion batteries and VOCs both pose a significant threat to the environment and human health. In this work, a series of high-performance α-MnO2 catalysts with metal dopant and acid treatment are synthesized from acid leaching solution of cathode materials, which were separated from spent lithium-ion manganese battery (SLMB). Compared with pure α-MnO2, all SLMB-MnO2 (α-MnO2 prepared from SLMB) exhibit better catalytic activities of VOCs oxidation. Among them, SLMB-MnO2-2, with a molar ratio value of KMnO4 to Mn2+ of 2, exhibits the best catalytic activity (T90 = 224 °C and 297 °C for toluene and chlorobenzene oxidation, respectively). By comparison of their physicochemical properties, it can be found that SLMB-MnO2-2 possesses a larger specific surface and abundant mesopores, better redox ability at low temperature, much more generation of oxygen vacancies, and abundant adsorbed oxygen species. Moreover, the suitable dopant of copper and appropriate concentration of acid treatment play a synergistic role in enhancing the catalytic performance of VOCs oxidation on SLMB-MnO2-2. Furthermore, combined with in-situ DRIFTS and TD/GC–MS, the catalytic mechanism of toluene oxidation is explored on SLMB-MnO2-2.