A novel chemical looping reforming coupled with staged gasification was proposed to recycle plastic waste for hydrogen production. A series of Fe-M-Al oxygen carriers (M: Mg, Ca, Mn, Mo, La, Ce) were synthesized used for staged chemical looping gasification (SCLG) of waste disposable masks. The activity, stability of oxygen carriers was studied and compared in relation to hydrogen content and syngas production. Physic-chemical properties of fresh and spent oxygen carriers were performed by N₂-isothermal adsorption/desorption, SEM, XRD, TPO, H₂-TPR to deeply investigate the role of oxygen carriers during SCLG. Results showed that compared with the controlled Fe-Al, all the six supports improved the porosity of oxygen carriers and provided higher performance towards hydrogen, due to the enhanced interaction between Fe and supports. Fe-Ca-Al showed the optimum activity, with the carbon conversion and syngas yield of 99.03% and 177.89 mmol/gOC, respectively. Fe-Mg-Al possessed the highest CO selectivity, with a CO/(CO+CO₂) ratio of 90.40%. The oxygen diffusion ability of oxygen carrier was enhanced by the introduction of Mo and Mn, which can be demonstrated by the high CO₂ content of product gases during the reduction stage. Compared to other oxygen carriers, Fe-Mo-Al exhibited better catalytic activity in water splitting reactions, which may due to its excellent thermal stability. Further investigation into the cycle stability found that syngas production from plastic decreased from 177.89 mmol/gOC in the first cycle to 124.99 mmol/gOC in the seventh cycle in the presence of Fe-Ca-Al resulted from the metal sintering. Whereas Fe-Mo-Al presented relatively stable yield during the cycle operation. The proposed staged chemical looping gasification with modified Fe-Al was demonstrated as a promising upcycling method for disposal plastic waste.

chemical looping gasification,plastic,iron based oxygen carrier,hydrogen