Upgrading landfill material into a high-value oxygen carrier for chemical looping combustion

The use of landfill material (LM) as oxygen carriers (OCs) in chemical looping combustion (CLC) of simulated municipal solid waste (MSW) syngas was investigated. Three LM samples were treated and tested as OCs for CLC. The results demonstrated that pure LMs exhibited poor regeneration ability and combustion efficiencies of less than or equal to 50 % at the tenth cycle, making them unsuitable as standalone OCs. However, given their diverse yet advantageous elemental composition, LMs were explored as potential supports for iron ore (IO) by substituting 50 % of IO with LMs. The performance of the resulting EIO (LM:IO = 1:1) samples demonstrated that EIO1 and EIO2 performed comparably to IO with average syngas combustion efficiencies of approximately 70 % for IO, EIO1, and EIO2. While EIO3 outperformed IO, exhibiting an increasing trend over 10 cycles with high CO and H₂ combustion efficiencies of 78.95 % and 85.01 %, respectively. The increasing trend was attributed to the presence of CaO and brownmillerite, unique to EIO3. Incorporating LMs into IO maintained or improved sintering resistance of the OCs. Characterizations of the OCs elucidated the transformations occurring during CLC and their impact on reactivity, physical properties, and overall performance. While pure LMs are unsuitable as OCs due to poor regeneration capabilities, their alkaline earth metal (AEM) content makes them effective as supports for IO. This research advances landfill sustainability by demonstrating the successful integration of LMs as a support for IO in CLC, resulting in a novel and cost-effective waste-derived OC for carbon capture technologies.