A novel spent LiNixCoyMn1−x−yO2 battery-modified mesoporous Al2O3 catalyst for H2-rich syngas production from catalytic steam co-gasification of pinewood sawdust and polyethylene

Introducing waste plastics with high hydrogen contents (such as polyethylene) into the biomass gasification process is an effective way to upgrade the syngas. Despite their good catalytic abilities, some of the transition metals commonly applied for the co-gasification of biomass and plastic wastes are of high cost and have poor availability, which requires developing affordable transition metal-based catalysts with desirable catalytic performances for producing H2-rich syngas. Spent lithium-ion batteries, which have a huge annual output and pose a great threat to the environment, contain a high potential to prepare efficient catalysts for biomass and plastic co-gasification due to the richness of active transition metals (e.g., Ni, Co and Mn). Therefore, in this study, a novel Ni/Co/Mn-loaded mesoporous Al2O3 catalyst was developed from the thermally decomposed spent LiNixCoyMn1−x−yO2 batteries (spent LIBs) for pinewood sawdust and polyethylene co-gasification as an effective means to achieve the zero-waste strategy. The results showed that Ni, Co and Mn could be non-selectively recycled from spent LIBs and uniformly loaded on γ-Al2O3 support, and the support's mesopores were well-retained (average pore diameters around 11 nm). The highest H2 productivity of the co-gasification could reach 17.16 mmol g−1 with a concentration of 36 vol% over the LIB-modified Al2O3. The modification by spent LIBs would enhance the catalyst's relative concentrations of acid-base sites in high-temperature regions, leading to the significant promotion of H2 productivity from 600 to 800 °C (151.3%). Nickel and manganese in the LIBs were primarily responsible for the catalysis since their nanosized particles could endow the catalyst with accessible and reducible metallic sites for volatile reforming. The synergy among the Ni, Co and Mn could evidently intensify the oxygen vacancies of the LIB-modified Al2O3 to promote the oxygen transfer reactions from steam to dissociative species for H2 production. This study provided a novel and promising technology for synergistic valorization of spent lithium-ion batteries, biomass residues and plastic wastes to produce value-added H2-rich syngas.