Hydrocracking is an attractive route for the deconstruction of polyolefins (PO). Limited mechanistic insights are available for PO deconstruction and it is unclear if insights from model compounds are directly transferable to PO systems. The current work establishes a mechanistic framework for PO hydrocracking and identifies reactivity descriptors to close the gap between model alkanes and PO. We assessed the role of each catalyst component on low-density polyethylene (LDPE) as a function of reaction conditions. Our results show the metal-to-acid site ratio (MAB) plays a significant role in LDPE hydrocracking. We demonstrate increasing the catalyst MAB controls the distribution to larger alkanes and enhances the branching in the residual polymer. Furthermore, we highlight key similarities and differences in the hydrocracking of model alkanes and LDPE and propose a new macromolecular hydrocracking mechanism that diverges from small alkanes. Extensive characterization of the catalyst and products were conducted to provide structure-reactivity relations.

Mechanistic insights into the hydrocracking of polyolefin plastics waste

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.