Promotion effect of cobalt doping on microwave-initiated plastic deconstruction for hydrogen production over iron catalysts

Microwave-initiated deconstruction of plastic into hydrogen and high-value carbons is an attractive upcycling technology. However, the interplay between microwave field and catalyst material and the reaction mechanism were not fully understood. In this study, Co doping Fe-Al catalysts were synthesized for hydrogen production from LDPE using microwave and conventional heating. The Fe1Co1Al2 catalyst yielded hydrogen at 61.39 mmol/gplastic under microwave, which was almost two times higher than conventional heating. Characterization indicated Co doped spinel iron catalyst under microwave rapidly transformed into the highly active FeCo alloy for plastic dehydrogenation. The microwave field was responsible for the rapid formation of FeCo, as it enhanced the charge transfer from H to Fe. The Co doping also inhibited the formation of Fe3C during plastic deconstruction, which changed the carbon diffusion pathway and promoted the formation of nanotubes and hydrogen production.