Novel synthesis of activated biochar-supported catalysts for pyrolysis of cardboard waste derived from express package

Abstract

The acid leaching process is a mature technology that can recover valuable metals from the Ni-Co-Mn cathode from spent lithium-ion batteries (LIBs). This work studied the modification of activated biochar using the leaching solution. It was confirmed that the HCl leaching process had a high recovery efficiency of metals (e.g., Li, Ni, Co, Mn) than the H3PO4 leaching process. Furthermore, the modified biochar exhibited excellent catalytic performance in the cellulose-rich biomass (e.g., cardboard waste) pyrolysis. In general, the modified biochar could significantly improve the pyrolysis efficiency in terms of activation energy reduction. The Ea of cardboard waste pyrolysis was decreased from 110.61 kJ/mol to 77.46 kJ/mol. Moreover, the presence of modified biochar could remarkably enhance the transformation of anhydrosugars to hydrocarbons (e.g., long-chain alkanes). Particularly, the modified biochar rich in the transition metals (e.g., Ni) could enhance the conversion of light oxygenates (e.g., aldehydes, ketones) and furans to hydrocarbons. The modified biochar could greatly reduce the content of oxygenated components such as anhydrosugars (e.g., levoglucosenone - LGO), ketones, and aldehydes, which were transformed into light hydrocarbons (e.g., alkenes). The content of hydrocarbons was increased nearly-two times from 12 % to 24 % during pyrolysis of cardboard waste. Therefore, the modified biochar has a high potential to be used in catalytic biomass pyrolysis in the aspects of improving the pyrolysis efficiency and upgrading the pyrolysis products.