Coking Reduction of Cr‐loaded Beta Zeolite during Polymer Cracking: Hydrocracking of Aromatics by Synergistic Effect of Cr6+ and Zeolitic Acid Sites

Abstract

AbstractZeolite deactivation induced by coke deposition is a critical problem in the industrialization of the chemical recycling (CR) of plastics. We previously demonstrated that Cr6+ species bonded to silanol groups in the zeolite framework inhibit coke deposition in low‐density polyethylene (LDPE) cracking. In this study, the role of Cr6+ species and the mechanism of coke reduction were determined experimentally. During LDPE cracking, hydrogen was generated from the alkane products at the Cr6+ sites. Furthermore, the hydrogenation and decomposition of aromatics, which are coke precursors, occurred at the zeolitic acid sites, resulting in the reduction of coke deposition. Owing to the synergistic effect of the Cr6+ and zeolitic acid sites, coke reduction was achieved without reducing cracking activity.