Pilot-scale validation of FCC equilibrium catalyst rejuvenation using PVC as an in situ HCl source: an integrated waste valorization strategy

Spent FCC equilibrium catalysts (ECAT) progressively lose activity due to the accumulation of contaminant metals such as Fe and Ni, which block access to active sites and worsen product distribution. In this work, a simple and integrated rejuvenation route is proposed that uses waste poly(vinyl chloride) (PVC) as an in situ HCl source under hydrothermal treatment conditions. During treatment, PVC releases HCl, which promotes partial removal and redistribution of contaminant species while restoring catalyst acidity and accessibility. Two industrial ECAT samples were treated and characterized by XRD, FIB-SEM, AAS, argon physisorption, and NH 3 -TPD. The results showed partial removal of metallic contaminants, with Fe being removed more effectively than Ni, preservation of the FAU crystalline structure and particle morphology, and a significant increase in total acidity after treatment. Although some reduction in surface area and mesopore volume was observed, the rejuvenated catalysts exhibited improved performance in cracking triisopropylbenzene and n-hexane, particularly for the bulkier probe molecule, indicating enhanced accessibility to external and near-surface acid sites. To assess practical applicability, the most responsive sample was further evaluated in a pilot-scale Micro Downflow Unit under FCC-relevant conditions. The addition of rejuvenated ECAT to the catalyst inventory produced a conversion response close to that obtained with the addition of fresh FCC catalyst and shifted the product distribution toward lighter fractions at isoconversion. These results demonstrate that PVC-assisted rejuvenation can recover a substantial fraction of ECAT cracking functionality while simultaneously valorizing plastic waste, offering a promising circular route for more sustainable FCC catalyst management.