Hydrogen production synergy in non-thermal plasma copyrolysis of low-density polyethylene and cellulose

The production of hydrogen from plastic and biomass waste via processes powered by renewable electricity can be a pivotal contributor to an effective waste management system in a circular economy. Copyrolysis of plastic and biomass waste mixtures can be economically appealing, not only by eliminating the need for waste stream separation but also by potentially synergizing hydrogen production. In this study, we present evidence of such hydrogen production synergy in plasma copyrolysis of mixtures of low-density polyethylene (LDPE) and cellulose (CE) as plastic and biomass waste models, respectively. We treated samples made of mixtures of LDPE and CE powders at five different mass ratios, ranging from 100% LDPE to 100% CE. We used non-thermal nitrogen plasma and argon plasma in a Streamer Dielectric-Barrier Discharge (SDBD) configuration under atmospheric pressure conditions. Synergistic hydrogen production was observed when nitrogen was used as the working gas, but not with argon, resulting in up to 37% greater hydrogen production compared to non-synergistic expectations. This outcome is attributed to the nitrogen-doped oxygenated carbonaceous residues from CE pyrolysis catalyzing the dehydrogenation and reforming of light alkanes resulting from the decomposition of LDPE.