Catalytic\nUpgrading of Pyrolysis Condensables from\nPostconsumer Polyolefins Using HZSM‑5

The conversion of plastic wastes to monomeric olefins\nis an attractive\nmeans for achieving a plastic circular economy. In our study, a fluidized\nbed reactor converts post-consumer\nwaste high-density polyethylene (HDPE) and polypropylene (PP) to mostly\ncondensed pyrolysis waxes and some oils, preventing carbon loss to\ngases. The pyrolysis condensables were upgraded to light olefins (C<sub>2</sub>–C<sub>5</sub>) at carbon yields greater than 76 wt\n% using the HZSM-5 zeolite catalyst at a post pyrolysis process that\nemployed a micropyrolyzer. These results were comparable to olefin\nmonomer yields from direct <i>ex situ</i> catalytic pyrolysis\nof the original waste plastics without condensing the vapors, highlighting\nthe potential applicability of this approach in plastic waste recycling.\nOur results suggest that a centralized catalytic upgrading facility\nfed by pyrolysis condensables sourced from distributed thermochemical\nprocessing plants is a promising pathway to a circular economy. Such\nan approach enables utilization of available catalytic cracking infrastructure\nwhile focusing on setting up distributed thermochemical processing\nplants close to material recovery facilities. The energy-dense pyrolysis\nwaxes are more suitable for transportation, contributing to the overall\nscalability and economic viability of the proposed distributed approach.