Catalytic pyrolysis of cellulose with biochar modified by Ni-Co-Mn cathode material recovered from spent lithium-ion...

In this study, we investigated the recycling of Ni-Co-Mn cathode materials from spent LIBs by an acid leaching process using H₃PO₄ and HCl. The leaching liquor was then used to modify the biochar applied during the catalytic pyrolysis of the biomass. The addition of char catalysts decreased the maximum decomposition rate and shifted it to a lower temperature. Accordingly, the activation energy (E_a) of cellulose pyrolysis decreased from 140.86 kJ/mol to 83.55 kJ/mol (char-P) and 89.42 kJ/mol (char-Cl). The char catalysts enhanced the transformation of the large-molecule components to small-molecule gases during cellulose pyrolysis. The addition of both char-P and char-Cl decreased the anhydrosugar content and increased the hydrocarbon content, suggesting their high catalytic activities in converting anhydrosugars to hydrocarbons (e.g., long-chain alkanes). The anhydrosugar content decreased from 17.8% to 11.1%, while the furan content increased from 5.1% to 15.2% with the addition of char-P. The addition of char-Cl resulted in a lower content of furans (4.8%) and a higher content of hydrocarbons (40.1%), mostly because of the increase in alkanes and aromatic compounds. Therefore, these char catalysts could be used for biomass pyrolysis in terms of activation energy reduction and upgrading the quality of the product. This win-win pyrolysis process is a promising pathway for the co-valorization of the cathode materials of spent LIBs and biomass waste.